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                                                                    EXHIBIT 10.1


                                    EXHIBIT A

                            JOINT REPORTING AGREEMENT

         In consideration of the mutual covenants herein contained, each of the
parties hereto represents to and agrees with the other parties as follows:

         1. Such party acknowledges that it is required and eligible to file a
statement on Schedule 13G pertaining to the common stock of Kosan Biosciences
Incorporated to which this agreement is an exhibit, for the filing of the
information contained therein.

         2. Such party is responsible for timely filing of such statement and
any amendments thereto, and for the completeness and accuracy of the information
concerning such party contained therein; provided that no such party is
responsible for the completeness or accuracy of the information concerning the
other party making the filing, unless such party knows or has reason to believe
that such information is inaccurate.

         3. Such party agrees that such statement is filed by and on behalf of
each such party and that any amendment thereto will be filed on behalf of each
such party.

         This agreement may be executed in one or more counterparts, each of
which shall be deemed to be an original instrument, but all of such counterparts
taken together shall constitute but one agreement.

Dated: February 13, 2001

                                    AG-BIOTECH CAPITAL, LLC

                                    By: VIRIDIAN MANAGEMENT, LLC, its Manager

                                    By: /s/ Helene S. Cohen
                                        -------------------------------------
                                        Helene S. Cohen, President

                                    SAVIA, S.A. de C.V.

                                    By: /s/ Carlos Gerardo Mahaud
                                        -------------------------------------
                                        Name: Carlos Gerardo Mahaud
                                              -------------------------------
                                        Title: Attorney in Fact
                                               ------------------------------

                                    ALFONSO ROMO GARZA

                                    /s/ Alfonso Romo Garza
                                        -------------------------------------