SC 13D

                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                  SCHEDULE 13D
                                 (Rule 13d-101)

            INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
           TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO
                                 RULE 13d-2(a)

                               (Amendment No. 3)*

                                  Vysis, Inc.

                                (Name of Issuer)

                                  Common Stock

                         (Title of Class of Securities)

                                   928961101

                                 (CUSIP Number)

                               Daniel B. Pinkert
                                BP America Inc.
                            200 East Randolph Drive
                                 Mail Code 2106
                            Chicago, Illinois 60601
                                 (312) 856-3025

            (Name, Address and Telephone Number of Person Authorized
                     to Receive Notices and Communications)

                                October 24, 2001

            (Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box
[ ].

Note. This document is being  electronically filed with the Commission using the
EDGAR System. See Rule 13d-7 for other parties to whom copies are to be sent.
                         (Continued on following pages)
                              (Page 1 of 10 Pages)
                             ---------------------
    *The remainder of this cover page should be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which would
alter disclosures provide in a prior cover page.

     The information required on the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("ACT") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other provisions of the Act (however, see
the Notes).


1

 NAME OF REPORTING PERSONS
 I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

 BP p.l.c.; IRS No.: None

2

 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)	 (a) [x]
		 	 	 	 	 	 	 	 	 (b) [  ]

3

 SEC USE ONLY



4

 SOURCE OF FUNDS (SEE INSTRUCTIONS)

	OO

5

     CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
     OR 2(e) [  ]


6

 CITIZENSHIP OR PLACE OF ORGANIZATION

	England and Wales

NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH
REPORTING
PERSON
WITH

7

 SOLE VOTING POWER

	-0-


8

 SHARED VOTING POWER

	6,662,682


9

 SOLE DISPOSITIVE POWER

	-0-


10

 SHARED DISPOSITIVE POWER

	6,662,682

11

 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

		6,662,682

12

     CHECK IF THE  AGGREGATE  AMOUNT IN ROW (11)  EXCLUDES  CERTAIN  SHARES (SEE
     INSTRUCTIONS) [ ]

13

 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

65.1% (based on 10,241,438 shares outstanding as reported in the Form 10-Q
quarterly report for the quarterly period ended June 30, 2001)

14

 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	CO



1

 NAME OF REPORTING PERSONS
 I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

		BP America Inc.; IRS No.: 94-2257553

2

 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)	 (a) [x]
		 	 	 	 	 	 	 	 	 (b) [  ]

3

 SEC USE ONLY



4

 SOURCE OF FUNDS (SEE INSTRUCTIONS)

	OO

5

     CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
     OR 2(e) [ ]



6

 CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH
REPORTING
PERSON
WITH

7

 SOLE VOTING POWER

	-0-


8

 SHARED VOTING POWER

	6,662,682


9

 SOLE DISPOSITIVE POWER

	-0-


10

 SHARED DISPOSITIVE POWER

	6,662,682

11

 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

		6,662,682

12

     CHECK IF THE  AGGREGATE  AMOUNT IN ROW (11)  EXCLUDES  CERTAIN  SHARES (SEE
     INSTRUCTIONS) [ ]


13

 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

65.1% (based on 10,241,438 shares outstanding as reported in the Form 10-Q
quarterly report for the quarterly period ended June 30, 2001)

14

 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	CO







1

 NAME OF REPORTING PERSONS
 I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

		BP Corporation North America Inc.; IRS No.: 36-1812780

2

 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)	 (a) [x]
		 	 	 	 	 	 	 	 	 (b) [  ]

3

 SEC USE ONLY



4

 SOURCE OF FUNDS (SEE INSTRUCTIONS)

	OO

5

     CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
     OR 2(e) [ ]



6

 CITIZENSHIP OR PLACE OF ORGANIZATION

	Indiana

NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH
REPORTING
PERSON
WITH

7

 SOLE VOTING POWER

	-0-


8

 SHARED VOTING POWER

	6,662,682


9

 SOLE DISPOSITIVE POWER

	-0-


10

 SHARED DISPOSITIVE POWER

	6,662,682

11

 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	 	6,662,682

12

     CHECK IF THE  AGGREGATE  AMOUNT IN ROW (11)  EXCLUDES  CERTAIN  SHARES (SEE
INSTRUCTIONS) [ ]


13

 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

65.1% (based on 10,241,438 shares outstanding as reported in the Form 10-Q
quarterly report for the quarterly period ended June 30, 2001)

14

 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	CO







1

 NAME OF REPORTING PERSONS
 I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

		Amoco Technology Company; IRS No.: 36-3247360

2

 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)	 (a) [x]
		 	 	 	 	 	 	 	 	 (b) [  ]

3

 SEC USE ONLY



4

 SOURCE OF FUNDS (SEE INSTRUCTIONS)

	OO

5

     CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d)
     OR 2(e) [ ]



6

 CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware
NUMBER OF
SHARES
BENEFICIALLY
OWNED BY
EACH
REPORTING
PERSON
WITH

7

 SOLE VOTING POWER

	-0-


8

 SHARED VOTING POWER

	6,662,682


9

 SOLE DISPOSITIVE POWER

	-0-


10

 SHARED DISPOSITIVE POWER

	6,662,682

11

 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	 	6,662,682

12

     CHECK IF THE  AGGREGATE  AMOUNT IN ROW (11)  EXCLUDES  CERTAIN  SHARES (SEE
     INSTRUCTIONS) [ ]


13

 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

65.1% (based on 10,241,438 shares outstanding as reported in the Form 10-Q
quarterly report for the quarterly period ended June 30, 2001)

14

 TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

	CO


                        RELATING TO THE COMMON STOCK OF
                                  VYSIS, INC.

     This  Amendment  No. 3 amends the Schedule 13D filed  February 20, 1998, as
amended by the Amendment No. 1 filed  September 23, 1999 and the Amendment No. 2
filed July 11, 2001  (collectively,  the "Schedule  13D").  Unless  specifically
hereby amended,  the information in the Schedule 13D remains  unchanged.  Unless
otherwise defined herein, all defined terms used herein have the same meaning as
in the Schedule 13D.

Item 2.         Identity and Background

     Item 2 to the Schedule 13D is hereby supplemented and amended as follows:

     There have been  changes to the  executive  officers  and  directors  of BP
p.l.c. which are reflected on the attached Schedule I.

Item 4. Purpose of Transaction.

     Item 4 is hereby amended in its entirety to read as follows:

     The  6,662,682  shares of Common Stock of Vysis owned by ATC,  constituting
65.1% of the outstanding Vysis Common Stock, are held as an investment.  ATC and
BP have determined that ATC's investment in Vysis Common Stock is not strategic.
As  previously  reported  ATC  and BP  have  been  evaluating  alternatives  for
divestment  of all or a portion of ATC's  holdings  in Vysis  Common  Stock.
     On  October  24,  2001,  Abbott   Laboratories,   an  Illinois  corporation
("Abbott"), Rainbow Acquisition Corp., a Delaware corporation and a wholly owned
subsidiary of Abbott ("Rainbow") and Vysis entered into an Agreement and Plan of
Merger, dated as of October 24, 2001 (the "Merger  Agreement"),  which provides,
among other things,  for the  acquisition  of Vysis by Abbott by means of a cash
tender offer (the "Offer") for all of the issued and outstanding shares of Vysis
Common Stock and for the  subsequent  merger (the  "Merger") of Rainbow with and
into Vysis upon the terms and subject to the  conditions set forth in the Merger
Agreement.
     Concurrently  with  Abbott,  Rainbow  and Vysis  entering  into the  Merger
Agreement,  Abbott,  Rainbow,  BP and ATC entered into a Stockholder  Agreement,
dated as of October  24,  2001 (the  "Stockholder  Agreement").

     Pursuant to the Stockholder Agreement,  ATC has agreed, among other things,
that it

     will  tender  all of its  shares  of Vysis  Common  Stock  into the Offer
     promptly,  but  not  later  than  the  fifth  business  day  following  the
     commencement  of the  Offer,  and  that it  will  not  withdraw  any of its
     tendered  shares  of  Vysis  Common  Stock  so  long as the  Offer  remains
     outstanding;

     will not (a) dispose of or transfer  any  interest in or encumber  any of
     its shares of Vysis  Common  Stock,  (b) deposit its shares of Vysis Common
     Stock into a voting trust,  enter into any voting  arrangement or grant any
     proxy with  respect to its shares of Vysis  Common  Stock,  or (c) take any
     other action that would  interfere with the  performance of its obligations
     under the Stockholder Agreement;

     will vote or consent its shares of Vysis Common Stock (a) in favor of the
     Merger and  approval and  adoption of the Merger  Agreement  and any action
     required in furtherance  thereof,  (b) against any action or agreement that
     would  result in a breach of any  representation,  warranty  or covenant of
     Vysis in the Merger  Agreement,  and (c)  against  any action or  agreement
     which  would  delay,  postpone or attempt to  discourage  the Merger or the
     Offer or cause a condition to the closing of the Merger or the Offer to not
     be capable of being satisfied;

     irrevocably grants to, and appoints,  Abbott and any Abbott's nominee its
     proxy and  attorney-in-fact  (with full power of  substitution)  during the
     term of the Stockholder Agreement to vote its shares of Vysis Common Stock,
     or grant a consent or approval in respect of the shares, in connection with
     any meeting of the  stockholders  of Vysis:  (a) in favor of the Merger and
     approval and adoption of the Merger  Agreement  and any action  required in
     furtherance  thereof, (b) against any action or agreement that would result
     in a breach of any  representation,  warranty  or  covenant of Vysis in the
     Merger  Agreement,  and (c)  against  any action or  agreement  which would
     delay, postpone or attempt to discourage the Merger or the Offer or cause a
     condition  to the  closing  of the Merger or the Offer to not be capable of
     being satisfied; and

     irrevocably  waives any rights of appraisal or rights to dissent from the
     Merger.


The Stockholder Agreement also provides that

     from the date of the  Stockholder  Agreement  until  the  earlier  of the
     effective  time  of the  Merger  or  the  termination  of  the  Stockholder
     Agreement,  ATC will not (and ATC will not  permit  any of its  affiliates,
     officers,  directors  or  employees  or any  investment  banker,  financial
     advisor, attorney, accountant or other representative retained by it or any
     affiliate  (collectively  "Stockholder  Representatives")  to)  directly or
     indirectly:  (a) solicit, initiate, engage in discussions or negotiate with
     anyone or take any other  action  intended or designed  to  facilitate  any
     inquiry or effort of anyone (other than Abbott) relating to any Alternative
     Acquisition  (which is  defined in the  Merger  Agreement  as any direct or
     indirect  acquisition  of all or a  substantial  part of the  business  and
     properties of Vysis or any of Vysis'  subsidiaries  or any capital stock of
     Vysis or any of Vysis'  subsidiaries,  whether  by  merger,  tender  offer,
     exchange offer, sale of assets or similar  transactions  involving Vysis or
     any Vysis' subsidiary,  division or operating or principal business unit of
     Vysis);  (b)  provide  information  with  respect  to Vysis  or any  Vysis'
     Subsidiary to anyone, other than Abbott, relating to a possible Alternative
     Acquisition by anyone,  other than Abbott;  or (c) enter into any agreement
     with   respect   to   any   proposal   for  an   Alternative   Acquisition.
     Notwithstanding the foregoing, prior to the acceptance for payment of Vysis
     Common Stock  pursuant to the Offer,  ATC may advise the board of directors
     of  Vysis  of  receipt  by it (or any  Stockholder  Representative)  of any
     unsolicited  proposal  for  an  Alternative   Acquisition  or  any  inquiry
     indicating  that anyone is considering  making or wishes to make a proposal
     for  an  Alternative  Acquisition.   It  should  be  noted  that  the  term
     "Stockholder  Representative" does not include Vysis, any Vysis' Subsidiary
     or any  representative  of Vysis;

     ATC will promptly, and not later than within 2 business days, will advise
     Abbott of receipt by it (or any Stockholder Representative) of any proposal
     for an  Alternative  Acquisition or any inquiry  indicating  that anyone is
     considering  making  or  wishes  to  make a  proposal  for  an  Alternative
     Acquisition,  identifying such person, and the financial and other material
     terms and  conditions  of any proposal for an  Alternative  Acquisition  or
     potential proposal for an Alternative  Acquisition;  and

     ATC and BP cease and cause to be  terminated  all existing  discussion or
     negotiations  conducted  by them or at their  behest  with  respect  to any
     Alternative  Acquisition,  and that BP will promptly direct UBS Warburg LLC
     to  cease  and  cause  to  be  terminated   all  existing   discussions  or
     negotiations conducted by it with respect to any Alternative Acquisition on
     behalf of BP or its affiliates.

     Pursuant to the  Stockholder  Agreement,  Abbott and  Rainbow,  among other
things,  have agreed that without the prior written consent of ATC, Rainbow will
not (a) reduce the number of shares of Vysis Common Stock  subject to the Offer,
(b)  reduce  the  price it agreed to pay for the  shares of Vysis  Common  Stock
tendered pursuant to the Offer, (c) add to the conditions set forth in Exhibit A
of the Merger  Agreement or modify such  conditions in a manner  adverse to ATC,
(d) extend the Offer other than as provided in the  Stockholder  Agreement,  (e)
change the form of  consideration  payable  in the Offer,  or (f) make any other
change or  modification  in any of the terms of the Offer in any manner  that is
adverse to ATC.

     The Stockholder Agreement,  other than certain provisions contained herein,
will  terminate  upon the  earlier  of:  (a) the date  upon  which  the Offer is
terminated  without  the  purchase  of shares  of Vysis  Common  Stock;  (b) the
termination of the Merger Agreement; or (c) the effective time of the Merger.

     In addition to the above,  the  Stockholder  Agreement  also contains other
covenants,  terms and conditions,  as well as certain customary  representations
and  warranties  of the  parties.  The  above  description  of  the  Stockholder
Agreement  is  qualified  in  its  entirety  by  reference  to  the  Stockholder
Agreement,  a copy of which is filed as Exhibit 3 to this Amendment No. 3 and is
specifically incorporated herein by reference in response to this Item 4.

     Except as set forth  above,  ATC and BP do not have any plans or  proposals
that relate to or would result in any of the actions  specified in clauses (a) -
(j) of Item 4 in Schedule 13D.

Item 5.		Interest in Securities of the Issuer.

     Item 5 is amended to include the following:

     See "Item 4. Purpose of  Transaction"  for a description of the Stockholder
Agreement  which is qualified  in its  entirety by reference to the  Stockholder
Agreement and is specifically incorporated herein by reference in answer to this
Item 5.

Item 6. Contracts, Arrangements, Understandings or Relationships with
        Respect to the Securities of the Issuer.

     Item 6 is  amended  to  include  the  following:

     See "Item 4. Purpose of  Transaction"  for a description of the Stockholder
Agreement  which is qualified  in its  entirety by reference to the  Stockholder
Agreement and is specifically incorporated herein by reference in answer to this
Item 6.

Item 7.		Material to be Filed as Exhibits.

     Item 7 is amended to include the following:

     Exhibit  2 Joint  Filing  agreement,  dated  October  25,  2001.
     Exhibit 3 Stockholder Agreement, dated as of October 24, 2001, by and among
Abbott Laboratories,  Rainbow Acquisition Corp., Amoco Technology Company and BP
America Inc.


SIGNATURE
After reasonable inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this Statement is true, complete and correct.
Dated:	October 25, 2001
BP p.l.c.

By:  /s/ Lesley Stockwell
     ------------------------
Name: L. J. Stockwell
Title: Assistant Company Secretary

BP America Inc.

By:  /s/ D. B. Pinkert
     ------------------------
Name: D. B. Pinkert
Title: Corporate Secretary


BP Corporation North America Inc.

By:  /s/ D. B. Pinkert
     ------------------------
Name: D. B. Pinkert
Title: Corporate Secretary


Amoco Technology Company

By:  /s/ D. B. Pinkert
     ------------------------
Name: D. B. Pinkert
Title: Vice President


                                   SCHEDULE I

                      DIRECTORS AND EXECUTIVE OFFICERS OF
                                   BP p.l.c.


     The name, citizenship,  present principal occupation or employment, and the
name of any  corporation  or other  organization  in which  such  employment  is
conducted,  or each of the directors and executive  officers as October 24, 2001
of BP p.l.c.  ("BP") is set forth below.  Except as set forth below, each of the
directors  and  executive  officers  is a citizen  of the  United  Kingdom.  The
business  address of each director and officer is BP p.l.c.,  Britannic House, 1
Finsbury Circus,  London EC2M 7BA,  England.  Unless otherwise  indicated,  each
occupation set forth  opposite an executive  officer's name refers to employment
with BP.


NAME                            PRESENT PRINCIPAL OCCUPATION OR
                                EMPLOYMENT
--------------------------------------------------------------------------------

Directors                       (Executive Officer positions noted,
                                 where applicable)
--------------------------------------------------------------------------------
P. D. Sutherland                Non-executive Chairman, Chairman and Managing
(Ireland)                       Director of Goldman Sachs International

Sir Ian Prosser                 Non-executive Deputy Chairman, Chairman of Six
                                Continents PLC

The Lord Browne of Madingley    Executive Director and Group Chief Executive


Dr. J.G.S. Buchanan             Executive Director and Chief Financial Officer
(British and New Zealand)

R. F. Chase                     Executive Director and Deputy Group Chief
                                Executive

W. D. Ford                      Executive Director, Refining and Marketing

Dr. B.E. Grote                  Executive Director, Chemicals

R. L. Olver                     Executive Director, Exploration and Production

J. H. Bryan                     Non-executive Director, Chairman of Sara Lee
(United States)                 Corporation

E. B. Davis, Jr.                Non-executive Director, President and Chief
(United States)                 Executive Officer of Alliant Energy

C. F. Knight                    Non-executive Director, Chairman of Emerson
(United States)                 Electric

F. A. Maljers                   Non-executive Director, Chairman of the
(Netherlands)                   Supervisory Boards of the Amsterdam
                                Concertgebouw N.V., KLM Royal Dutch Airlines and
                                Rotterdam School of Management, Erasmus
                                University

Dr. W. E. Massey                Non-executive Director, President of Morehouse
(United States)                 College

H. M. P. Miles                  Non-executive Director, Chairman of Johnson
                                Matthey

Sir Robin Nicholson             Non-executive Director, retired Chairman of
                                Pilkington Optronics

M. H. Wilson                    Non-executive Director, President and Chief
(Canada)                        Executive Officer of RT Capital Management


Sir. R. Wilson                  Non-executive Director, Chairman
                                 of Rio Tinto plc


Executive Officers

J. C. Hanratty                  Company Secretary
(New Zealand)

G. R. Bradley                   Assistant Secretary

L. J. Stockwell                 Assistant Secretary





                               	Index To Exhibits

Exhibit No.     Exhibit

2               Joint Filing agreement, dated October 25, 2001

3               Stockholder  Agreement,  dated as of October 24, 2001,  by and
                among Abbott Laboratories,  Rainbow  Acquisition  Corp., Amoco
                Technology Company and BP America Inc.

EX-2

                                                                       EXHIBIT 2


                             JOINT FILING AGREEMENT

     In accordance with Rule 13d-1(k)  promulgated under the Securities Exchange
Act of 1934,  the  undersigned  agree to the  joint  filing  of a  Statement  on
Schedule 13D  (including  any and all  amendments  thereto)  with respect to the
shares of Vysis,  Inc. and further  agree to the filing of this  agreement as an
Exhibit thereto. In addition,  each party to this Agreement expressly authorizes
each other party to this  Agreement to file on its behalf any and all amendments
to such Statement on Schedule 13D.

Date:  October 25, 2001

BP p.l.c.

By:     /s/ Lesley Stockwell
        ----------------------
Name:   L. J. Stockwell
Title:  Assistant Company
        Secretary


BP America Inc.

By:     /s/ D. B. Pinkert
        -------------------------
Name:   D. B. Pinkert
Title:  Corporate Secretary


BP Corporation North America
Inc.

By:     /s/ D. B. Pinkert
        -------------------------
Name:   D. B. Pinkert
Title:  Corporate Secretary


Amoco Technology Company

By:     /s/ D. B. Pinkert
        -------------------------
Name:   D. B. Pinkert
Title:  Vice President

EX-3

                             STOCKHOLDER AGREEMENT

     STOCKHOLDER  AGREEMENT (this "Agreement"),  dated as of October 24, 2001 by
and among  Abbott  Laboratories,  an Illinois  corporation  ("Parent"),  Rainbow
Acquisition  Corp.,  a Delaware  corporation  and a wholly owned  subsidiary  of
Parent  ("Sub"),   Amoco  Technology   Company,  a  Delaware   corporation  (the
"Stockholder") and BP America Inc., a Delaware  corporation ("BP").  Capitalized
terms used but not defined herein shall have the meanings ascribed to such terms
in the Merger Agreement (as defined below).

     WHEREAS,  the  Stockholder  is,  as of the  date  hereof,  the  record  and
beneficial owner of 6,662,682 shares of common stock, par value $0.001 per share
(the "Common Stock"),  of Vysis,  Inc., a Delaware  corporation (the "Company");

     WHEREAS,  Parent,  Sub and the Company  concurrently  herewith are entering
into an Agreement  and Plan of Merger,  dated as of the date hereof (the "Merger
Agreement"),  which  provides,  among other things,  for the  acquisition of the
Company by Parent by means of a cash tender  offer (the  "Offer") for all of the
issued  and  outstanding  shares  of  Common  Stock of the  Company  and for the
subsequent merger (the "Merger") of Sub with and into the Company upon the terms
and subject to the conditions set forth in the Merger  Agreement;

     WHEREAS, the Company Board has adopted resolutions  approving and declaring
advisable the Merger Agreement,  this Agreement and the other Transactions (such
approvals  having been made in accordance with the DGCL,  including for purposes
of Section 203 thereof); and

     WHEREAS,  as a condition to the willingness of Parent and Sub to enter into
the Merger  Agreement,  Parent has requested that the  Stockholder  and BP agree
and, in order to induce Parent and Sub to enter into the Merger  Agreement,  the
Stockholder and BP have agreed to enter into this Agreement.

     NOW,  THEREFORE,  in  consideration of the execution and delivery by Parent
and  Sub  of the  Merger  Agreement,  the  foregoing  premises  and  the  mutual
representations,  warranties,  covenants  and  agreements  set forth  herein and
therein, and other good and valuable consideration,  the receipt and sufficiency
of which are hereby acknowledged, the parties hereto agree as follows:

     SECTION  1.   Representations  and  Warranties  of  the  Stockholder.   The
Stockholder hereby represents and warrants to Parent and Sub as follows:

     (a) The Stockholder is the record and beneficial  owner (as defined in Rule
13d-3 under the Exchange Act,  which meaning will apply for all purposes of this
Agreement) of 6,662,682  shares of Common Stock (as may be adjusted from time to
time pursuant to Section 7 hereof,  the  "Shares").  Except for the Shares,  the
Stockholder  does  not  beneficially  own or  have  any  right  to  acquire  any
securities  of the Company,  nor is the  Stockholder  subject to any contract or
understanding  that obligates it to vote,  acquire,  or otherwise  dispose of or
transfer  any  interest in the Common Stock of the Company or the Shares or that
restricts its rights in the Shares in any way.

     (b) The Stockholder is a corporation  duly  incorporated,  validly existing
and in good standing under the laws of Delaware and has all corporate  power and
authority required to carry on its business as now conducted.

     (c) The  execution,  delivery and  performance  by the  Stockholder of this
Agreement  and  the   consummation  by  the  Stockholder  of  the   transactions
contemplated  hereby are within the corporate power of Stockholder and have been
duly and validly  authorized by all necessary  corporate  action.  Assuming that
this Agreement  constitutes the valid and binding  obligation of Parent, Sub and
BP,  this  Agreement   constitutes  the  valid  and  binding  agreement  of  the
Stockholder,  enforceable in accordance  with its terms subject to the effect of
any applicable  bankruptcy,  reorganization,  insolvency,  moratorium or similar
laws  affecting  creditors,  rights  generally  and to  the  effect  of  general
principles of equity (regardless of whether such enforceability is considered in
a proceeding in equity or at law).

     (d)  Neither  the  execution  and  delivery  of  this   Agreement  nor  the
consummation by the  Stockholder of the  transactions  contemplated  hereby will
result in a violation of, or a default under,  or conflict with, any contract or
understanding  of any kind to which the Stockholder is a party or by which it is
bound or to which the Shares are subject,  which in each of the foregoing  cases
would  materially  adversely  affect  Sub,  the  Purchaser  or the  transactions
contemplated hereby or by the Merger Agreement.  Consummation by the Stockholder
of the  transactions  contemplated  hereby  will not  violate,  or  require  any
consent,  approval or notice under, any provision of any judgment, order, law or
regulation applicable to the Stockholder or the Shares, except for any necessary
filing under the Exchange Act or the HSR Act, or any non-U.S.  merger control or
competition laws or any violation or consent,  approval or notice the failure of
which to obtain would not materially  adversely affect Sub, the Purchaser or the
transactions contemplated hereby or by the Merger Agreement.

     (e) The Shares and the certificates  representing the Shares are now and at
all  times  during  the term  hereof  will be held by the  Stockholder,  or by a
nominee or custodian for the benefit of the  Stockholder,  free and clear of all
liens,  claims,  security  interests,  proxies,  voting  trusts  or  agreements,
understandings or any other encumbrances  whatsoever  ("Liens"),  except for any
Permitted Liens or any arising  hereunder.  The Stockholder will transfer to Sub
good  title  to  the   Shares,   free  and  clear  of  all  Liens.

     SECTION 2.  Representations  and Warranties of BP. BP hereby represents and
warrants to Parent and Sub as follows:

     (a) BP is a corporation  duly  incorporated,  validly  existing and in good
standing under the laws of the State of Delaware and has all corporate power and
authority required to carry on its business as now conducted.

     (b) The execution, delivery and performance by BP of this Agreement and the
consummation  by BP of the  transactions  contemplated  hereby  are  within  the
corporate power of BP and have been duly and validly authorized by all necessary
corporate action. Assuming that this Agreement constitutes the valid and binding
obligation of Parent, Sub and Stockholder,  this Agreement constitutes the valid
and binding agreement of BP, enforceable in accordance with its terms subject to
the effect of any applicable bankruptcy, reorganization,  insolvency, moratorium
or similar  laws  affecting  creditors'  rights  generally  and to the effect of
general  principles  of equity  (regardless  of whether such  enforceability  is
considered in a proceeding  in equity or at law).

     (c)  Neither  the  execution  and  delivery  of  this   Agreement  nor  the
consummation  by BP of the  transactions  contemplated  hereby  will result in a
violation  of,  or  a  default   under,   or  conflict  with,  any  contract  or
understanding  of any  kind to which BP is a party or by which it is bound or to
which  the  Shares  are  subject,  which in each of the  foregoing  cases  would
materially adversely affect Sub, the Purchaser or the transactions  contemplated
hereby  or by the  Merger  Agreement.  Consummation  by BP of  the  transactions
contemplated hereby will not violate, or require any consent, approval or notice
under, any provision of any judgment,  order, law or regulation applicable to BP
or the Shares,  except for any necessary  filing under the Exchange Act, the HSR
Act,  any  non-U.S.  merger  control or  competition  laws or any  violation  or
consent,  approval or notice the failure of which to obtain would not materially
adversely affect Sub, the Purchaser or the transactions  contemplated  hereby or
by the Merger Agreement.

     SECTION 3. Representations and Warranties of Parent and Sub. Each of Parent
and  Sub  hereby,  jointly  and  severally,   represents  and  warrants  to  the
Stockholder as follows:

     (a) Each of Parent  and Sub is a  corporation  duly  incorporated,  validly
existing  and  in  good  standing  under  the  laws  of  its   jurisdiction   of
incorporation and has all corporate power and authority required to carry on its
business as now conducted.

     (b) The  execution,  delivery  and  performance  by Parent  and Sub of this
Agreement  and  the   consummation  by  Parent  and  Sub  of  the   transactions
contemplated  hereby are within the corporate  powers of Parent and Sub and have
been duly and validly  authorized by all necessary  corporate  action.  Assuming
that  this  Agreement  constitutes  the  valid  and  binding  obligation  of the
Stockholder and BP, this Agreement  constitutes the valid and binding  agreement
of each of Parent and Sub,  enforceable in accordance  with its terms subject to
the effect of any applicable bankruptcy, reorganization,  insolvency, moratorium
or similar  laws  affecting  creditors'  rights  generally  and to the effect of
general  principles  of equity  (regardless  of whether such  enforceability  is
considered in a proceeding  in equity or at law).

     (c)  Neither  the  execution  and  delivery  of  this   Agreement  nor  the
consummation by each of Parent and Sub of the transactions  contemplated  hereby
will  result in a  violation  of, or a default  under,  or  conflict  with,  any
contract  or  understanding  of any kind to which  either  of Parent or Sub is a
party or bound, which in each of the foregoing cases would materially  adversely
affect the  Stockholder,  BP or the transactions  contemplated  hereby or by the
Merger Agreement. The consummation by each of Parent and Sub of the transactions
contemplated hereby will not violate, or require any consent, approval or notice
under,  any provision of any judgment,  order,  law or regulation  applicable to
either Parent or Sub,  except for any  necessary  filing under the Exchange Act,
the HSR Act, or any non-U.S. merger control or competition laws which in each of
the foregoing cases would materially adversely affect the Stockholder, BP or the
transactions contemplated hereby or by the Merger Agreement.

     SECTION  4.  Purchase  and  Sale of the  Shares;  Terms of  Offer.

     (a) The  Stockholder  hereby  agrees that it shall  tender and sell all the
Shares  into the  Offer  promptly,  and in any  event no  later  than the  fifth
Business Day  following  the  commencement  of the Offer,  and that it shall not
withdraw any Shares so tendered so long as the Offer  remains  outstanding.

     (b) Prior to tendering such Shares into the Offer,  the  Stockholder  shall
execute and deliver to Parent an affidavit  stating,  under  penalty of perjury,
the Stockholder's taxpayer identification number and that the Stockholder is not
a  foreign  person  as  defined  in  Section  1445 of the Code and the  treasury
regulations  thereunder.  The Stockholder  will receive the same price per Share
received by the other stockholders of the Company in the Offer. Sub's obligation
to accept  for  payment  and pay for the  Shares in the Offer is  subject to the
terms and conditions of the Offer set forth in the Merger  Agreement and Exhibit
A thereto.  Parent and Sub agree that in no event  shall the Shares be  accepted
for payment by Parent,  Sub or any Affiliate thereof until the early termination
or expiration of the  applicable  waiting period under the HSR Act has occurred.

     (c) Parent and Sub hereby agree that without the prior  written  consent of
the  Stockholder,  Sub shall  not:  (i)  reduce  the number of shares of Company
Common Stock subject to the Offer; (ii) reduce the Offer Price; (iii) add to the
conditions  set forth in  Exhibit A of the  Merger  Agreement;  (iv)  modify the
conditions set forth in Exhibit A of the Merger Agreement in a manner adverse to
the Stockholder;  (v) except as provided in the next sentence, extend the Offer;
(vi) change the form of  consideration  payable in the Offer;  or (vii) make any
other change or modification in any of the terms of the Offer in any manner that
is adverse to the  Stockholder.  Notwithstanding  the  foregoing,  (A) Sub shall
extend the Offer for one or more periods if at the initial scheduled  expiration
date or any  subsequent  expiration  date of the Offer any of the  conditions to
Sub's obligation to purchase shares of Company Common Stock are not satisfied or
waived,  until such time as such  conditions  are  satisfied  or waived (but not
after the Outside Date) and (B) Sub may, without the consent of the Stockholder,
(1)  extend the Offer if all of the  conditions  to the Offer are  satisfied  or
waived but the number of the Shares  validly  tendered and not withdrawn is less
than ninety percent (90%) of the Fully Diluted Shares,  for an aggregate  period
not to exceed  twenty (20) Business  Days (for all such  extensions);  provided,
that Sub shall immediately  accept and promptly pay for all Company Common Stock
tendered  prior to the date of an  extension  pursuant  to clause  (1) and shall
otherwise  meet the  requirements  of Rule  14d-11  under  the  Exchange  Act in
connection  with each such  extension,  and (2)  extend the Offer for any period
required by any rule,  regulation,  interpretation or position of the SEC or the
staff thereof applicable to the Offer.

     SECTION  5.  Transfer  of the  Shares.  Prior  to the  termination  of this
Agreement,  except as otherwise  provided herein, the Stockholder shall not: (a)
sell,  pledge or  otherwise  dispose of or transfer  any interest in or encumber
with any Lien any of the Shares;  (b)  deposit  the Shares into a voting  trust,
enter into a voting agreement or arrangement with respect to the Shares or grant
any proxy with respect to the Shares;  or (c) take any other action with respect
to the  Shares  that  would in any way  restrict,  limit or  interfere  with the
performance  of  its  obligations  hereunder  or the  transactions  contemplated
hereby. If the Stockholder acquires any additional shares of Common Stock of the
Company prior to the termination of this Agreement,  any such additional  shares
shall be deemed  Shares and  included in the Shares  subject to this  Agreement.

     SECTION 6. Voting of Shares;  Grant of  Irrevocable  Proxy;  Appointment of
Proxy.

     (a) The Stockholder  hereby agrees that, during the term of this Agreement,
at any meeting  (whether  annual or special and whether or not an  adjourned  or
postponed meeting) of the stockholders of the Company, or in connection with any
written consent of the stockholders of the Company,  the Stockholder will appear
at the meeting or  otherwise  cause the Shares to be counted as present  thereat
for purposes of  establishing a quorum and vote or consent (or cause to be voted
or consented)  the Shares:  (i) in favor of the Merger and approval and adoption
of the Merger  Agreement and any action  required in furtherance  thereof;  (ii)
against  any  action  or  agreement  that  would  result  in  a  breach  of  any
representation, warranty or covenant of the Company in the Merger Agreement; and
(iii) against any action or agreement which would delay,  postpone or attempt to
discourage  the Merger or the Offer or cause a  condition  to the closing of the
Merger or the Offer to not be capable of being  satisfied.

     (b) The Stockholder hereby irrevocably grants to, and appoints,  Parent and
any  nominee  thereof,  its  proxy  and  attorney-in-fact  (with  full  power of
substitution) during the term of this Agreement,  for and in the name, place and
stead of the Stockholder,  to vote the Shares, or grant a consent or approval in
respect of the Shares, in connection with any meeting of the stockholders of the
Company:  (i) in favor of the Merger and  approval  and  adoption  of the Merger
Agreement  and any action  required in  furtherance  thereof;  (ii)  against any
action  or  agreement  that  would  result  in a breach  of any  representation,
warranty or covenant of the Company in the Merger  Agreement;  and (iii) against
any action or agreement which would delay, postpone or attempt to discourage the
Merger or the Offer or cause a  condition  to the  closing  of the Merger or the
Offer to not be capable of being satisfied.

     (c) The Stockholder  represents that any outstanding proxy heretofore given
in respect of the Shares,  if any, is revocable and that any  outstanding  proxy
heretofore given in respect of the Shares has been revoked.


     (d) The Stockholder  hereby affirms that the irrevocable proxy set forth in
this  Section  6 is  given  in  connection  with  the  execution  of the  Merger
Agreement, and that such irrevocable proxy is given to secure the performance of
the duties of the  Stockholder  under this  Agreement.  The  Stockholder  hereby
further  affirms that the  irrevocable  proxy is coupled with an interest and is
intended to be irrevocable  in accordance  with the provisions of Section 212(e)
of the DGCL.

     (e) The Stockholder  hereby  irrevocably  waives any rights of appraisal or
rights to dissent  from the Merger  that the  Stockholder  may have.

     SECTION 7. Certain Events. In the event of any stock split, stock dividend,
merger,  reorganization,   recapitalization  or  other  change  in  the  capital
structure  of the  Company  affecting  the  Common  Stock of the  Company or the
acquisition  of  additional  shares  of  Common  Stock  of  the  Company  by the
Stockholder,  the number of Shares  shall be  adjusted  appropriately,  and this
Agreement and the obligations hereunder shall attach to any additional shares of
Common Stock or other  securities or rights of the Company issued to or acquired
by the Stockholder.

     SECTION 8. Certain Other Agreements.

     (a) From the date of this Agreement until the earlier of the Effective Time
or the  termination  of this  Agreement,  the  Stockholder  shall  not  (and the
Stockholder  will not  permit  any of its  Affiliates,  officers,  directors  or
employees or any investment banker, financial advisor,  attorney,  accountant or
other representative retained by it or any Affiliate (collectively  "Stockholder
Representatives") to) directly or indirectly:  (i) solicit,  initiate, engage in
discussions  or negotiate  with any Person or take any other action  intended or
designed to  facilitate  any inquiry or effort of any Person (other than Parent)
relating to any Alternative  Acquisition;  (ii) provide information with respect
to the  Company or any Company  Subsidiary  to any  Person,  other than  Parent,
relating to a possible Alternative Acquisition by any Person, other than Parent;
or  (iii)  enter  into  any  agreement  with  respect  to  any  proposal  for an
Alternative  Acquisition Proposal.  Notwithstanding the foregoing,  prior to the
acceptance for payment of Common Stock of the Company pursuant to the Offer, the
Stockholder  may advise the Company  Board of receipt by it (or any  Stockholder
Representative)  of any  unsolicited  Alternative  Acquisition  Proposal  or any
inquiry  indicating  that any Person is considering  making or wishes to make an
Alternative  Acquisition Proposal.  Notwithstanding the foregoing,  it is agreed
and understood by the parties that the term "Stockholder  Representative"  shall
not include the Company,  any Company Subsidiary or any Company  Representative.


     (b) The  Stockholder  promptly,  and in any event  within two (2)  Business
Days,  shall  advise  Parent in writing  of  receipt  by it (or any  Stockholder
Representative)  of any Alternative  Proposal or any inquiry indicating that any
Person  is  considering  making or  wishes  to make an  Alternative  Acquisition
Proposal,  identifying  such Person,  and the financial and other material terms
and conditions of any Alternative  Acquisition Proposal or potential Alternative
Acquisition  Proposal.  The  obligations  provided  for in this  Section 8 shall
become  effective  immediately  following  the  execution  and  delivery of this
Agreement by the parties hereto.

     (c) The Stockholder and BP hereby agree to cease and cause to be terminated
immediately  all existing  discussions or  negotiations  conducted by them or at
their  behest  heretofore  with  respect  to  any  Alternative  Acquisition.  In
addition,  BP agrees to promptly direct UBS Warburg LLC to cease and cause to be
terminated  immediately all existing discussions or negotiations conducted by it
heretofore  with respect to any  Alternative  Acquisition on behalf of BP or its
Affiliates.

     (d) Notwithstanding any other provision of this Agreement,  the Stockholder
shall be liable to, and shall defend, indemnify and hold harmless,  Parent, Sub,
the Company,  each Company Subsidiary and their respective  officers,  directors
and affiliates (the "Indemnified Parties"):  (i) for any and all Taxes of BP and
any  current or former  Affiliate  of BP (other  than the Company or any Company
Subsidiary) for any taxable period  beginning before the Closing Date, for which
the  Company  or any  Company  Subsidiary  may be liable  pursuant  to  Treasury
Regulation Sec.  1.1502-6 (or any similar  provision of state,  local or foreign
law), as a transferee or successor,  by contract,  agreement or otherwise;  (ii)
any and all Taxes  imposed  on or with  respect to the  Company  or any  Company
Subsidiary  for any  taxable  period (or  portion  thereof)  ending on or before
February 10, 1998 (all amounts described in clauses (i) and (ii) of this Section
8(d) being, the "Indemnified Taxes"); and (iii) any and all expenses incurred by
any Indemnified  Party arising from any  Indemnified  Taxes  (collectively,  the
"Stockholder  Indemnification  Obligations").

     (e) BP hereby irrevocably and unconditionally guarantees any and all of the
Stockholder Indemnification Obligations.

     (f) BP hereby agrees that it shall pay any fees,  expenses or other amounts
that  become due and  payable by the  Company  to UBS  Warburg  LLC or any other
investment bank or financial  advisor engaged by the Company other than Wachovia
Securities  (formerly  known as First Union  Securities) and Goldman Sachs & Co.
(such  entities  other than  Wachovia  Securities  and Goldman  Sachs & Co., the
"Covered  Advisors")  as a result  of the  Transactions  (the  "Covered  Advisor
Liabilities")  and shall defend,  indemnify  and hold  harmless the  Indemnified
Parties  against any claims for such amounts or any liabilities or costs arising
out of or resulting  from any claims for such amounts.  In the event any Covered
Advisor makes any written claim or demand for the payment of any Covered Advisor
Liabilities (a "Demand"),  Parent shall promptly, but in no event more than five
(5) Business  Days  following  such  Demand,  notify BP of such claim or demand,
provided,  however,  that  Parent's  failure  to notify BP within  such five (5)
Business  Day period  shall  relieve  BP of its  obligation  to pay the  Covered
Advisor  Liabilities  only to the extent that BP is actually  prejudiced by such
failure. BP shall have the right to dispute any Demand and defend Parent and the
Company by appropriate  proceedings  against any Demand and shall have the power
to direct and control such  defense.  All costs and  expenses  incurred by BP in
defending  such Demand shall be the  liability  of, and shall be paid by, BP. If
the Company or Parent desires to  participate in any such defense,  or to employ
separate  counsel  of its  choice,  it may do so at its sole  cost and  expense.
Parent and each of its Affiliates shall cooperate with BP and its counsel in the
defense  of any  Demand.  Neither  Parent nor any of its  Affiliates  shall make
payment on, or  otherwise  settle,  a Demand  without the consent of BP.  Parent
shall give BP and its counsel access to the relevant  business records and other
documents  of the Company,  and shall permit them to consult with the  employees
and counsel of the Company and any of its  Affiliates  (during  normal  business
hours  and  without  undue  disruption  to  the  Company's  Business)  as may be
reasonably necessary in connection with the foregoing.

     SECTION 9. Further Assurances;  Stockholder  Capacity.

     (a)  With  respect  to  each  party's  respective  obligations  under  this
Agreement,  the Stockholder and BP shall, upon request of Parent or Sub, execute
and  deliver  any  additional  documents  and take such  further  actions as may
reasonably  be  deemed  by  Parent  or Sub to be  necessary  to  carry  out  the
provisions  hereof and to vest the power to vote the Shares as  contemplated  by
Section 6 hereof in Parent.

     (b) Nothing in this  Agreement  shall be  construed  to prohibit any person
from taking any action  solely in his or her capacity as a member of the Company
Board to the extent specifically permitted by the Merger Agreement.

     SECTION 10. Termination.  This Agreement, and all rights and obligations of
the parties  hereunder,  shall  terminate upon the earlier of: (a) the date upon
which the Offer is  terminated  without the  purchase of shares of Common  Stock
thereunder  in  accordance  with its terms;  (b) the  termination  of the Merger
Agreement in accordance  with its terms;  or (c) the Effective  Time;  provided,
however, that whether or not the Merger is consummated, the provisions set forth
in  Sections 11 and 12 shall  survive any  termination  of this  Agreement;  and
provided,  further,  that the provisions set forth in Sections 8(b), 8(c), 8(d),
8(e),  and 8(f) shall  survive  following  the  Effective  Time if the Merger is
consummated.


     SECTION 11. Expenses.  Except as otherwise  provided  herein,  all fees and
expenses  incurred by any one party hereto shall be borne by the party incurring
such fees and expenses.

     SECTION 12. Miscellaneous.

     (a) All notices,  requests,  claims, demands and other communications under
this  Agreement  shall be in  writing  and  shall be deemed  given if  delivered
personally  or sent by overnight  courier  (providing  proof of delivery) to the
following  addresses (or at such other address for a party as shall be specified
by like notice):

(A) if to Parent or Sub, to:

Abbott Laboratories
100 Abbott Park Road
D-920, AP6C
Abbott Park, Illinois 60064-3500
Attention:      Senior Vice President, Diagnostic Operations

with a copy to:

Abbott Laboratories
100 Abbott Park Road
D-364, AP6D
Abbott Park, Illinois 60064-3500
Attention:      Senior Vice President, Secretary and General
                Counsel

with a copy to:

Skadden, Arps, Slate, Meagher & Flom (Illinois)
333 West Wacker Drive
Chicago, Illinois 60606
Attention:      Charles W. Mulaney, Jr.
                Brian W. Duwe

and

(B) if to the Stockholder or BP, to:

BP America Inc.
200 E. Randolph Drive
Chicago, Illinois 60601
Attention:      Vice President - Mergers and Acquisitions

with a copy to:

Sullivan & Cromwell
125 Broad Street
New York, New York  10023
Attention:      John J. O'Brien

     (b) The headings  contained in this  Agreement are for  reference  purposes
only and  shall not  affect in any way the  meaning  or  interpretation  of this
Agreement.

     (c) This  Agreement  may be executed in two or more  counterparts,  each of
which shall be deemed an original but all of which shall be  considered  one and
the same agreement.

     (d) This Agreement  (including the Merger Agreement and any other documents
and  instruments  referred  to herein)  constitutes  the entire  agreement,  and
supersedes all prior  agreements and  understandings,  whether  written or oral,
among the parties hereto with respect to the subject matter hereof.

     (e) This Agreement shall be governed by, and construed in accordance  with,
the laws of the State of Delaware,  without  giving effect to the  principles of
conflict of laws thereof.

     (f) Neither this Agreement nor any of the rights,  interests or obligations
hereunder  shall  be  assigned,  in whole or in  part,  by  operation  of law or
otherwise by any of the parties  without the prior written  consent of the other
parties.  Any purported  assignment  without such consent shall be void,  except
that  Sub may  assign,  in its  sole  discretion,  any of or all of its  rights,
interests  and  obligations  under  this  Agreement  to Parent or to one or more
direct or indirect wholly owned Subsidiaries of Parent or a combination thereof,
but no such assignment  shall relieve Sub or any of its  obligations  under this
Agreement.  Subject to the preceding  sentence,  this  Agreement will be binding
upon,  inure to the  benefit  of, and be  enforceable  by, the parties and their
respective successors and assigns.

     (g) If any term,  provision,  covenant or  restriction  herein is held by a
court of  competent  jurisdiction  or other  authority  to be  invalid,  void or
unenforceable or against public policy, the remainder of the terms,  provisions,
covenants  and  restrictions  of this  Agreement  shall remain in full force and
effect and shall in no way be affected, impaired or invalidated.

     (h) The parties agree that irreparable damage would occur in the event that
any of the provisions of this Agreement is not performed in accordance  with its
specific terms or were  otherwise  breached.  It is accordingly  agreed that the
parties shall be entitled to an injunction or injunctions to prevent breaches of
this  Agreement  and to enforce  specifically  the terms and  provisions of this
Agreement in any Delaware  state court or any federal court located in the State
of  Delaware,  this  being in  addition  to any other  remedy to which  they are
entitled  at law or in equity.  In  addition,  each of the parties  hereto:  (i)
consents to submit  itself to the personal  jurisdiction  of any Delaware  state
court or any  federal  court  located in the State of  Delaware in the event any
dispute  arises out of this  Agreement;  (ii) agrees that it will not attempt to
deny or defeat such personal  jurisdiction  by motion or other request for leave
from any such court;  (iii) agrees that it will not bring any action relating to
this  Agreement in any court other than any Delaware  state court or any federal
court  sitting in the State of  Delaware;  and (iv) waives any right to trial by
jury with respect to any action related to or arising out of this Agreement.

     (i) No amendment, modification or waiver in respect of this Agreement shall
be effective  against any party unless it shall be in writing and signed by such
party.


     IN WITNESS  WHEREOF,  Parent,  Sub, the Stockholder and BP have caused this
Agreement to be duly executed and delivered as of the date first written above.


ABBOTT LABORATORIES



By:
        --------------------
        Name:
        Title:


RAINBOW ACQUISITION CORP.



By:
        --------------------
        Name:
        Title:


AMOCO TECHNOLOGY COMPANY



By:
        --------------------
        Name:
        Title:


BP AMERICA INC.



By:
        --------------------
        Name:
        Title: