SPECIAL POWER OF ATTORNEY

1.	Appointment of Attorney in Fact.  I, MARC J. GURWITH, designate
	LANCE K. GORDON, DONALD P. FRANCIS and CARTER A. LEE, and
	each of	them, as my attorney in fact to execute any and all
	Forms 3, Forms 4 or Forms 5 as required pursuant to Section
	16 of the Securities Exchange Act of 1934, as amended, and to
	file the same with the Securities and Exchange Commission.

2.	Effectiveness.  This Power of Attorney shall become effecive
	immediately.

3.	Duration.  This Power of Attorney becomes effective as
	provided in Section 2 and shall remain in effect until
	revoked	or terminated as provided in Section 4 or 5,
	notwithstanding my incapacity or disability, or any
	uncertainty as to whether I am dead or alive.

4.	Revocation.  This Power of Attorney may be revoded,
	suspended, or terminated by written notice from me to my
	attorney in fact.

5.	Termination
	(a)	By Guardian.  If appointed, a guardian of my estate
		may, with court approval, revoke, suspend, or
		terminate this Power of	Attorney.

	(b)	By Death of Principal.  My death shall revoke this
		Power of Attorney upon actual knowledge or receipt
		of written notice thereof by the attorney in fact.

	(c)	By Expiration.  This Power of Attorney shall
		terminate at midnight, December 31, 2003.
		The termination of this Power of Attorney shall not
		affect acts lawfully taken hereunder during the
		period of its effectiveness.

6.	Reliance.  Any person dealing with the attorney in fact shall
	be entitled to rely upon this Power of Attorney so long as
	the person with whom the attorney in fact was dealing, at the
	time notice of any revocation, suspension or termination of
	this Power of Attorney. Any action so taken, unless otherwise
	invalid or unenforcable, shall be binding on me and my heirs,
	devisees, legatees or personal representatives.

7.	Applicable Law.  The internal law of the State of California
	shall govern this Power of Attorney.


Signature:  	/s/ Marc J. Gurwith

Print Name: 	Marc J. Gurwith

Date:		January 31, 2003