[  *  ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission  pursuant  to  Rule  24b-2 of the Securities Exchange Act of 1934, as
amended.

                                                                   Exhibit 10.37






                   STOCK PURCHASE AND STOCK ISSUANCE AGREEMENT

                                     BETWEEN


                         SMITHKLINE BEECHAM CORPORATION
                                       AND

                                 EXELIXIS, INC.

                                   DATED AS OF
                                OCTOBER 28, 2002


                                  TABLE OF CONTENTS

                                                                     PAGE
ARTICLE I
DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   1
     Affiliate. . . . . . . . . . . . . . . . . . . . . . . . . . . .   2
     Change of Control. . . . . . . . . . . . . . . . . . . . . . . .   2
     Closing. . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2
     Common Stock . . . . . . . . . . . . . . . . . . . . . . . . . .   2
     Deferral Notice. . . . . . . . . . . . . . . . . . . . . . . . .   2
     Deferral Period. . . . . . . . . . . . . . . . . . . . . . . . .   2
     Development Term . . . . . . . . . . . . . . . . . . . . . . . .   2
     DWAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   2
     Effective Date . . . . . . . . . . . . . . . . . . . . . . . . .   2
     Exchange Act . . . . . . . . . . . . . . . . . . . . . . . . . .   2
     Exercise Notice. . . . . . . . . . . . . . . . . . . . . . . . .   2
     Expanded Program Option. . . . . . . . . . . . . . . . . . . . .   2
     Expanded Program Option Shares . . . . . . . . . . . . . . . . .   2
     Extension Period . . . . . . . . . . . . . . . . . . . . . . . .   2
     Fair Market Value. . . . . . . . . . . . . . . . . . . . . . . .   3
     Financial Statements . . . . . . . . . . . . . . . . . . . . . .   3
     Form 10-K. . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     Form 10-Q. . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     Governmental Authority . . . . . . . . . . . . . . . . . . . . .   3
     HSR Act. . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     Initial Closing. . . . . . . . . . . . . . . . . . . . . . . . .   3
     Initial Shares . . . . . . . . . . . . . . . . . . . . . . . . .   3
     Intellectual Property. . . . . . . . . . . . . . . . . . . . . .   3
     Legal Proceeding . . . . . . . . . . . . . . . . . . . . . . . .   3
     Limited Program Option . . . . . . . . . . . . . . . . . . . . .   3
     Limited Program Option Shares. . . . . . . . . . . . . . . . . .   3
     Limited Release Date . . . . . . . . . . . . . . . . . . . . . .   3
     Loan Documents . . . . . . . . . . . . . . . . . . . . . . . . .   3
     Material Adverse Effect. . . . . . . . . . . . . . . . . . . . .   3
     Material Agreement . . . . . . . . . . . . . . . . . . . . . . .   4
     Material Breach. . . . . . . . . . . . . . . . . . . . . . . . .   4
     Material Event . . . . . . . . . . . . . . . . . . . . . . . . .   4
     National Securities Market . . . . . . . . . . . . . . . . . . .   4
     OfficerCertificate . . . . . . . . . . . . . . . . . . . . . . .   4
     Operating Documents. . . . . . . . . . . . . . . . . . . . . . .   4
     Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     Option Closing Date. . . . . . . . . . . . . . . . . . . . . . .   4
     Option Exercise Date . . . . . . . . . . . . . . . . . . . . . .   4
     Option Shares. . . . . . . . . . . . . . . . . . . . . . . . . .   4
     Permitted Transferee . . . . . . . . . . . . . . . . . . . . . .   4
     Person . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     Registrable Shares . . . . . . . . . . . . . . . . . . . . . . .   4
     Registration Expenses. . . . . . . . . . . . . . . . . . . . . .   4
     Registration Statement . . . . . . . . . . . . . . . . . . . . .   4
     Registration Trigger Date. . . . . . . . . . . . . . . . . . . .   4
     Restricted Period. . . . . . . . . . . . . . . . . . . . . . . .   4
     Rule 144 . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     SEC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     SEC Affiliate. . . . . . . . . . . . . . . . . . . . . . . . . .   4
     SEC Filings. . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     Securities Act . . . . . . . . . . . . . . . . . . . . . . . . .   5
     Selling Expenses . . . . . . . . . . . . . . . . . . . . . . . .   5
     Shares . . . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     Standstill Period. . . . . . . . . . . . . . . . . . . . . . . .   5
     Stock Repayment. . . . . . . . . . . . . . . . . . . . . . . . .   5
     Stock Repayment Amount . . . . . . . . . . . . . . . . . . . . .   5
     Stock Repayment Closing Date . . . . . . . . . . . . . . . . . .   5
     Stock Repayment Notice . . . . . . . . . . . . . . . . . . . . .   5
     Stock Repayment Shares . . . . . . . . . . . . . . . . . . . . .   5
     Transaction Documents. . . . . . . . . . . . . . . . . . . . . .   5
     Third Party. . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     Trading Day. . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     United States or U.S.. . . . . . . . . . . . . . . . . . . . . .   5
ARTICLE 2
AUTHORIZATION AND ISSUANCE OF THE SHARES. . . . . . . . . . . . . . .   5
     Authorization. . . . . . . . . . . . . . . . . . . . . . . . . .   5
     Issuance and Sale of the Initial Shares. . . . . . . . . . . . .   5
     Issuance, Sale, Pricing and Conditions of the Option Shares. . .   5
       The Expanded Program Option. . . . . . . . . . . . . . . . . .   6
       The Limited Program Option . . . . . . . . . . . . . . . . . .   6
     Issuance of the Stock Repayment Shares . . . . . . . . . . . . .   6
     Conditional Limitation on Ownership. . . . . . . . . . . . . . .   7
ARTICLE 3
CLOSING; DELIVERY; NOTICE . . . . . . . . . . . . . . . . . . . . . .   7
     Initial Closing. . . . . . . . . . . . . . . . . . . . . . . . .   7
     Payment and Delivery of the Initial Shares . . . . . . . . . . .   7
       Payment. . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
       Delivery . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     Payment and Delivery of the Option Shares. . . . . . . . . . . .   8
       Notice . . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
       Payment. . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
       Delivery . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     The Stock Repayment Shares . . . . . . . . . . . . . . . . . . .   8
       Notice . . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
       Stock Repayment Closings . . . . . . . . . . . . . . . . . . .   8
     Delivery; Satisfaction of Obligation . . . . . . . . . . . . . .   8
     Location . . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
ARTICLE 4
REPRESENTATIONS AND WARRANTIES OF EXELIXIS. . . . . . . . . . . . . .   9
     Organization, Good Standings and Qualification.  Exelixis. . . .   9
     Authorization; Due Execution . . . . . . . . . . . . . . . . . .   9
     Capital Stock. . . . . . . . . . . . . . . . . . . . . . . . . .  10
     Validity of Shares . . . . . . . . . . . . . . . . . . . . . . .  10
     SEC Filings; Financial Statements. . . . . . . . . . . . . . . .  10
       SEC Filings. . . . . . . . . . . . . . . . . . . . . . . . . .  10
       Financial Statements . . . . . . . . . . . . . . . . . . . . .  11
       No Material Adverse Effect . . . . . . . . . . . . . . . . . .  11
     Litigation . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
     Governmental Consents. . . . . . . . . . . . . . . . . . . . . .  11
     Compliance with Applicable Laws and Other Instruments. . . . . .  12
     Compliance with Environmental Laws . . . . . . . . . . . . . . .  12
     Taxes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     Insurance. . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     Properties . . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     Intellectual Property. . . . . . . . . . . . . . . . . . . . . .  13
     Effect of Representations and Warranties . . . . . . . . . . . .  13
ARTICLE 5
REPRESENTATIONS AND WARRANTIES OF GSK; RESTRICTIONS ON TRANSFER OF
THE SHARES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  13
     Representations and Warranties . . . . . . . . . . . . . . . . .  13
       Corporate Organization and Authority . . . . . . . . . . . . .  13
       Authorization; Due Execution . . . . . . . . . . . . . . . . .  13
       Investment Only. . . . . . . . . . . . . . . . . . . . . . . .  14
       Experience . . . . . . . . . . . . . . . . . . . . . . . . . .  14
       Accredited Purchaser . . . . . . . . . . . . . . . . . . . . .  14
     No Registration. . . . . . . . . . . . . . . . . . . . . . . . .  14
     Limitations on Transfer. . . . . . . . . . . . . . . . . . . . .  14
     Legend . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  14
ARTICLE 6
CONDITIONS TO CLOSING . . . . . . . . . . . . . . . . . . . . . . . .  15
     Conditions to Obligations of GSK to Consummate each Closing. . .  15
     Conditions to Obligations of Exelixis to Consummate each Closing  17
ARTICLE 7
ADDITIONAL AGREEMENTS; LOCK UP; STANDSTILL. . . . . . . . . . . . . .  17
     Registration of Shares . . . . . . . . . . . . . . . . . . . . .  17
       Registration Requirements. . . . . . . . . . . . . . . . . . .  17
       Incidental Registration. . . . . . . . . . . . . . . . . . . .  18
       Registration Expenses. . . . . . . . . . . . . . . . . . . . .  19
       Registration Suspension. . . . . . . . . . . . . . . . . . . .  19
       Registration Procedures. . . . . . . . . . . . . . . . . . . .  20
       Indemnification. . . . . . . . . . . . . . . . . . . . . . . .  20
     Filings. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  22
     Other Actions. . . . . . . . . . . . . . . . . . . . . . . . . .  22
     Lock Up and Selling Restrictions . . . . . . . . . . . . . . . .  22
     Standstill . . . . . . . . . . . . . . . . . . . . . . . . . . .  23
     Conditions Eliminating Standstill. . . . . . . . . . . . . . . .  24
     Conditions Eliminating Lock Up . . . . . . . . . . . . . . . . .  24
     Use of Proceeds. . . . . . . . . . . . . . . . . . . . . . . . .  25
     Exelixis Repurchase Option . . . . . . . . . . . . . . . . . . .  25
ARTICLE 8
MISCELLANEOUS . . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
     Publicity. . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
     Dispute Resolution . . . . . . . . . . . . . . . . . . . . . . .  26
     Governing Law. . . . . . . . . . . . . . . . . . . . . . . . . .  26
     Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
     Performance Warranty . . . . . . . . . . . . . . . . . . . . . .  26
     Notices. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  26
     Force Majeure. . . . . . . . . . . . . . . . . . . . . . . . . .  28
     Waiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  28
     Severability . . . . . . . . . . . . . . . . . . . . . . . . . .  28
     Entire Agreement . . . . . . . . . . . . . . . . . . . . . . . .  28
     Headings . . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
     Use of Name. . . . . . . . . . . . . . . . . . . . . . . . . . .  29
     Further Actions. . . . . . . . . . . . . . . . . . . . . . . . .  29
     Survival of Representations and Warranties . . . . . . . . . . .  29
     Parties in Interest. . . . . . . . . . . . . . . . . . . . . . .  29
     Construction of Agreement. . . . . . . . . . . . . . . . . . . .  29
     Counterparts . . . . . . . . . . . . . . . . . . . . . . . . . .  29
     FinderFees . . . . . . . . . . . . . . . . . . . . . . . . . . .  29
     Waiver of Jury Trial . . . . . . . . . . . . . . . . . . . . . .  30



                                LIST OF SCHEDULES

     SCHEDULE  4.3     SCHEDULE  OF  OUTSTANDING  SECURITIES

     SCHEDULE  4.6     DISCLOSURE  OF  OUTSTANDING  LITIGATION









[  *  ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission  pursuant  to  Rule  24b-2 of the Securities Exchange Act of 1934, as
amended.


                   STOCK PURCHASE AND STOCK ISSUANCE AGREEMENT

THIS  STOCK  PURCHASE  AND  STOCK  ISSUANCE  AGREEMENT  (the  "Stock  Purchase
Agreement")  is  made  and  entered  into as of October 28, 2002 (the "Effective
Date")  by  and  between  EXELIXIS,  INC.,  a  Delaware  corporation, having its
principal  place  of  business  at  170  Harbor  Way,  P.O.  Box  511, South San
Francisco,  California 94083 ("Exelixis"), and SMITHKLINE BEECHAM CORPORATION, a
Pennsylvania corporation doing business as GlaxoSmithKline ("GSK"). Exelixis and
GSK  are sometimes referred to herein individually as a "Party" and collectively
as  the  "Parties."

                                    RECITALS

     A.  Exelixis  and  GSK  have  entered into that certain Product Development
and  Commercialization  Agreement  of  even  date  herewith  (the  "Development
Agreement") and the Loan and Security Agreement of even date herewith (the "Loan
Agreement")  (this  Stock  Purchase  Agreement,  Development  Agreement and Loan
Agreement,  are  collectively referred to herein as the "Transaction Documents")
and,  in  connection  with,  and as a condition of entering into the Development
Agreement,  the  Parties  desire  to  enter  into  this Stock Purchase Agreement
providing  for  the  purchase  of  capital  stock  of  Exelixis  by  GSK.

     B.  Exelixis  desires  to  sell  to GSK, and GSK desires to make an initial
purchase  from Exelixis of Two Million (2,000,000) shares (the "Initial Shares")
of Exelixis' common stock, par value $0.001 per share (the "Common Stock"), upon
the  Initial  Closing  (as  defined  in  Section  3.1).

     C.  Exelixis  and  GSK  desire to provide for the possibility of additional
     purchases  by GSK of up to [*] shares of Common Stock, at Exelixis' option,
     in  accordance  with  the terms and conditions set forth herein, subject to
     the  reduction  of  the  number  of  shares  as  provided  in  Section 2.2.

     D. Exelixis and GSK desire to provide for the issuance of additional shares
of  Common  Stock  that  may  be  issued, at Exelixis' option, such option to be
dependent on terms and conditions contained in the Loan Agreement and this Stock
Purchase  Agreement, in repayment of any outstanding loan amounts under the Loan
Agreement  (the  "Stock  Repayment  Shares").

     NOW,  THEREFORE,  in consideration of the foregoing recitals and the mutual
covenants  and  agreements  contained  herein,  and  for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
Parties  hereto,  intending  to  be  legally  bound, do hereby agree as follows:

                                    ARTICLE I
                                   DEFINITIONS

     Unless  otherwise defined in this Stock Purchase Agreement, all capitalized
terms  shall  have  the  meanings given them in the Development Agreement or the
Loan  Agreement.  As  used in this Stock Purchase Agreement, the following terms
shall  have  the  following  respective  meanings:

     1.1  "Affiliate"  shall  mean  any  Person,  whether  de  jure or de facto,
which directly or indirectly through one (1) or more intermediaries controls, is
controlled  by  or  is under common control with, a Party to this Stock Purchase
Agreement.  A Person shall be deemed to "control" another Person if it (i) owns,
directly or indirectly, beneficially or legally, at least fifty percent (50%) of
the  outstanding  voting  securities or capital stock (or such lesser percentage
which  is  the  maximum  allowed  to  be  owned  by  a  Person  in  a particular
jurisdiction)  of  such other Person, or has other comparable ownership interest
with  respect  to  any  Person  other than a corporation; or (ii) has the power,
whether  pursuant  to  contract, ownership of securities or otherwise, to direct
the  management  and  policies  of  the  Person.

     1.2  "Change  of  Control"  shall mean a transaction in which [ * ].

     1.3  "Closing"  shall  have  the  meaning  set  forth  in  Section  3.4.2.

     1.4  "Common  Stock"  shall  have  the  meaning  set  forth  in  Recital B.

     1.5  "Deferral Notice" shall have the meaning set forth in Section 7.1.4(b)

     1.6  "Deferral Period" shall have the meaning set forth in Section 7.1.4(b)

     1.7 "Development Term" shall have the meaning set forth in Section 3.1.1 of
the  Development  Agreement,  as  it  may  be  amended  from  time  to  time.

     1.8  "DWAC"  shall  have  the  meaning  set  forth  in  Section  3.4.3.

     1.9  "Effective  Date" shall have the meaning set forth in the introductory
paragraph.

     1.10  "Exchange  Act" means the Securities Exchange Act of 1934, as amended
from  time  to  time,  and  the  rules  and  regulations promulgated thereunder.

     1.11  "Exercise  Notice"  shall  have  the  meaning  set  forth  in Section
3.3.1.

     1.12  "Expanded Program Option" shall have the meaning set forth in Section
2.3.1.

     1.13  "Expanded  Program Option Shares" shall have the meaning set forth in
Section  2.3.1.

     1.14  "Extension  Period" shall have the meaning set forth in Section 3.1.2
of  the  Development  Agreement,  as  it  may  be  amended  from  time  to time.

     1.15  "Fair  Market Value" shall have the meaning set forth in Section 2.4.

     1.16  "Financial  Statements"  shall  have the meaning set forth in Section
4.5.2.

     1.17 "Form 10-K" shall mean an annual report filed by Exelixis with the SEC
pursuant  to  Section  13  or  15(d)  of  the  Exchange  Act.

     1.18  "Form  10-Q" shall mean a quarterly report filed by Exelixis with the
SEC  pursuant  to  Section  13  or  15(d)  of  the  Exchange  Act.

     1.19  "Governmental Authority" means any nation or government, any state or
other  political  subdivision  thereof, any central bank (or similar monetary or
regulatory  authority)  thereof,  any  entity exercising executive, legislative,
judicial, regulatory or administrative functions of or pertaining to government,
and  any  corporation  or  other  entity  owned  or controlled, through stock or
capital  ownership  or  otherwise,  by  any  of  the  foregoing.

     1.20  "HSR  Act"  means the Hart-Scott-Rodino Antitrust Improvements Act of
1976,  as  amended.

     1.21.  "Initial  Closing"  shall have the meaning set forth in Section 3.1.

     1.22  "Initial  Shares"  shall  have  the  meaning  set forth in Recital B.

     1.23  "Intellectual  Property" shall have the meaning set forth in the Loan
Agreement.

     1.24  "Legal  Proceeding"  shall  mean  any  action,  suit,  litigation,
arbitration,  proceeding  (including  any  civil,  criminal,  administrative,
governmental  or  appellate proceeding), hearing, inquiry, audit, examination or
investigation  commenced, brought, conducted or heard by or before, or otherwise
involving,  any  court  or  other  Governmental  Authority  or any arbitrator or
arbitration  panel.

     1.25  "Limited  Program Option" shall have the meaning set forth in Section
2.3.2.

     1.26  "Limited  Program  Option Shares" shall have the meaning set forth in
Section  2.3.2.

     1.27  "Limited  Release  Date"  shall have the meaning set forth in Section
7.4.2.

     1.28  "Loan  Documents" shall have the meaning set forth in Section 1.45 of
the  Loan  Agreement.

     1.29  "Material Adverse Effect" shall mean any material adverse effect upon
(a)  the  validity  or enforceability of this Stock Purchase Agreement or any of
the  transactions  contemplated  by  this  Stock  Purchase Agreement, (b) on the
business,  operations,  condition  (financial  or  otherwise),  performance  or
properties  of Exelixis taken as a whole, or (c) upon the ability of Exelixis to
fulfill  any  of  its  obligations  under  this  Stock  Purchase  Agreement.

     1.30  "Material  Agreement"  shall  mean  any  agreement  which is filed by
Exelixis  as  part  of  its  SEC  Filings.

     1.31  "Material  Breach" shall have the meaning set forth in Section 12.2.1
of  the  Development  Agreement.

     1.32  "Material  Event"  shall have the meaning set forth in Section 7.1.4.

     1.33  "National  Securities  Market"  shall mean the Nasdaq National Market
System,  The  Nasdaq  SmallCap  Market  and any other national public securities
exchange.

     1.34  "Officer's  Certificate"  shall have the meaning set forth in Section
6.1.2.

     1.35  "Operating  Documents"  shall  mean  Exelixis'  amended  and restated
certificate  of  incorporation, as filed with the State of Delaware, amended and
restated  bylaws,  and  all  modifications  and  amendments  thereto.

     1.36  "Option"  shall  have  the  meaning  set  forth  in  Section  2.3.

     1.37  "Option  Closing  Date"  shall  have the meaning set forth in Section
3.3.2.

     1.38  "Option  Exercise  Date"  shall have the meaning set forth in Section
3.3.1.

     1.39  "Option  Shares"  shall  have the meaning set forth in Section 2.3.2.

     1.40  "Permitted  Transferee"  shall  have the meaning set forth in Section
7.4.3.

     1.41  "Person"  means  an  individual,  corporation,  partnership,  limited
liability  company,  joint  venture,  association,  trust,  unincorporated
organization  or  other  entity.

     1.42  "Registrable  Shares"  shall  have  the  meaning set forth in Section
7.1.1(a).

     1.43  "Registration  Expenses"  shall have the meaning set forth in Section
7.1.3.

     1.44  "Resale  Registration  Statement" shall have the meaning set forth in
Section  7.1.1(a).

     1.45  "Registration  Trigger  Date"  shall  have  the  meaning set forth in
Section  7.1.1(a).

     1.46 "Restricted Period" shall have the meaning set forth in Section 7.4.1.

     1.47  "Rule  144"  shall  have  the  meaning  set  forth  in  Section  5.3.

     1.48  "SEC"  means  the  United  States Securities and Exchange Commission.

     1.49  "SEC  Affiliate"  shall  have  the  meaning  ascribed  to  the  term
"affiliate"  under  Rule  144  of  the  Securities  Act.

     1.50  "SEC  Filings"  shall  have  the  meaning set forth in Section 4.5.1.

     1.51  "Securities  Act"  means  the Securities Act of 1933, as amended from
time  to  time,  and  the  rules  and  regulations  promulgated  thereunder.

     1.52  "Selling Expenses" shall have the meaning set forth in Section 7.1.3.

     1.53  "Shares"  shall  have  the  meaning  set  forth  in  Section  2.1.

     1.54  "Standstill  Period" shall have the meaning set forth in Section 7.5.

     1.55  "Stock  Repayment"  shall  have the meaning set forth in Section 2.4.

     1.56  "Stock  Repayment Amount" shall have the meaning set forth in Section
2.4.

     1.57  "Stock  Repayment  Closing  Date" shall have the meaning set forth in
Section  3.4.2.

     1.58  "Stock  Repayment Notice" shall have the meaning set forth in Section
3.4.1.

     1.59 "Stock Repayment Shares" shall have the meaning set forth in Recital D

     1.60 "Transaction Documents" shall have the meaning set forth in Recital A.

     1.61  "Third  Party"  shall  mean any Person other than GSK or Exelixis and
their  respective  Affiliates.

     1.62  "Trading  Day" means a day on which the principal National Securities
Market  on which Exelixis Common Stock is trading or listed is open for trading.

     1.63  "United  States"  or  "U.S." shall mean the United States of America.

                                    ARTICLE 2
                    AUTHORIZATION AND ISSUANCE OF THE SHARES

     2.1  Authorization.  Exelixis  has,  or  shall  have  prior  to  the
applicable issuance, authorized the issuance and sale of the Initial Shares, the
Option  Shares  and  the  Stock  Repayment  Shares  (collectively, the "Shares")
pursuant  to  the  terms  and  conditions  hereof.

     2.2  Issuance  and  Sale  of  the  Initial Shares. Subject to the terms and
conditions of this Stock Purchase Agreement, on the date of the Initial Closing,
Exelixis  shall issue and sell to GSK, and GSK shall purchase from Exelixis, the
Initial Shares, at a purchase price per share equal to Seven Dollars ($7.00) per
share, or a total purchase price of Fourteen Million Dollars ($14,000,000.00) in
the  aggregate.

     2.3  Issuance,  Sale,  Pricing  and  Conditions  of  the  Option  Shares.
Subject  to  the  terms  and  conditions  set  forth  in this Section 2.3 and in
Sections  2.5  and  3.3  hereof, Exelixis, in its sole discretion, shall have an
option  to  issue  and  sell to GSK (the "Option"), and upon the exercise of the
Option  by  Exelixis,  GSK  shall  be  obligated  to purchase from Exelixis, the
Expanded  Program Option Shares or the Limited Program Option Shares as follows.

          2.3.1 The Expanded Program Option. Subject to the terms and conditions
hereof  and  Section  2.3.2  below,  if  GSK selects its Expanded Program Option
pursuant  to  Section 3.5.1(b) of the Development Agreement, Exelixis shall have
the  Option  to require GSK to purchase from Exelixis up to [*] shares of Common
Stock  (the  "Expanded  Program  Option  Shares"), at a purchase price per share
equal  to  [*]  of  the average of the opening and closing sale prices of Common
Stock  as  reported  by the National Securities Market on which the Common Stock
trades or is listed for the first twenty (20) consecutive Trading Days following
the date which is two (2) Trading Days after Exelixis' filing of its most recent
Form  10-Q or Form 10-K; provided, however, that in the event that the per share
price of the Expanded Program Option Shares would result in an aggregate payment
by  GSK  of  greater than [*], then the number of Expanded Program Option Shares
shall  be  reduced  to the nearest such number of whole shares and payment shall
approach  as  closely  as possible, but not exceed, [*]. Exelixis shall exercise
its  option to require GSK to purchase the Expanded Program Option Shares, if at
all, not later than thirty (30) Trading Days after the date that GSK selects the
Expanded  Program Option, by notifying GSK of the number of shares it wishes GSK
to  purchase.  The purchase of the Expanded Program Option Shares shall close on
the  date  which  is  fifteen  (15) Trading Days after the date of such Exercise
Notice.

          2.3.2 The Limited Program Option. Notwithstanding Section 2.3.1 above,
if GSK selects or is deemed to have selected the Limited Program Option pursuant
to Section 3.5.1(a) of the Development Agreement, Exelixis shall have the Option
to  require  GSK to purchase from Exelixis up to [*] shares of Common Stock (the
"Limited  Program  Option  Shares"),  (the Expanded Program Option Shares or the
Limited  Program  Option  Shares,  each  sometimes  referred  to  as the "Option
Shares"),  instead of the Expanded Program Option Shares at a purchase price per
share  equal  to  [*]  of  the average of the opening and closing sale prices of
Common  Stock  as reported by the National Securities Market on which the Common
Stock  trades  or  is  listed for the first twenty (20) consecutive Trading Days
following  the  date which is two (2) Trading Days after Exelixis' filing of its
most  recent  Form  10-Q or Form 10-K; provided, however, that in the event that
the  per  share  price  of  the Limited Program Option Shares would result in an
aggregate payment by GSK of greater than [*], then the number of Limited Program
Option  Shares  shall  be reduced to the nearest such number of whole shares and
payment  shall  approach  as  closely as possible, but not exceed, [*]. Exelixis
shall  exercise its option to require GSK to purchase the Limited Program Option
Shares,  if  at  all, not later than thirty (30) Trading Days after the date GSK
selects  or  is deemed to have selected the Limited Program Option, by notifying
GSK  of  the  number  of  shares  it wishes GSK to purchase. The purchase of the
Limited  Program  Option  Shares  shall  close on the date which is fifteen (15)
Trading  Days  after  the  date  of  such  Exercise  Notice.

     2.4  Issuance  of  the  Stock  Repayment  Shares.  Subject  to  the  terms
and  conditions  set  forth  in  this  Stock  Purchase  Agreement  and  the Loan
Agreement,  Exelixis  shall  have  an option to issue to GSK the Stock Repayment
Shares  in payment of all or any portion of the then due principal amount of any
Advance  (as  defined  in  the Loan Agreement) and all accrued interest relating
thereto up to and including any of the Payment Dates described in Section 5.1(a)
of  the  Loan Agreement (the "Stock Repayment Amount") (each such instance being
hereinafter  referred to as a "Stock Repayment"). The number of shares of Common
Stock  comprising  the  Stock Repayment Shares issuable in connection with Stock
Repayments  shall  be  equal  to  the quotient of the applicable Stock Repayment
Amount  divided  by  the  Fair  Market  Value (as defined below) of one share of
Common  Stock.  No  fractional shares shall be issued in connection with a Stock
Repayment.  The  "Fair  Market  Value" of the Common Stock shall be deemed to be
the  average  of  the  opening  and  closing  sale prices of the Common Stock as
reported  by  the National Securities Market on which the Common Stock trades or
is  listed  for  the  first  twenty  (20)  consecutive  Trading Days immediately
following  the  date which is two (2) Trading Days after Exelixis filed its most
recent  Form  10-Q or Form 10-K prior to the date of the Stock Repayment Notice.

     2.5  Conditional  Limitation  on  Ownership.  Notwithstanding  anything  to
the  contrary  contained  in  this Stock Purchase Agreement, the total number of
shares  of  Common  Stock  owned  by  GSK  acquired  pursuant to the Transaction
Documents shall at all times be less than twenty percent (20%) of Exelixis' then
outstanding Common Stock, as reported in Exelixis' most recent Form 10-Q or Form
10-K.  In  the  event  that  any  purchase of Option Shares or the acceptance of
Stock Repayment Shares would cause GSK to be a holder of twenty percent (20%) or
more  of  Exelixis'  then outstanding Common Stock, GSK shall be relieved of its
obligations  to  make  such purchase(s) or accept such Stock Repayment Shares to
the extent that the Shares acquired by GSK pursuant to the Transaction Documents
would  be  equal  to  or  exceed  such  twenty  percent  (20%)  threshold.  For
clarification,  the  twenty  percent (20%) ownership test shall be calculated in
each  instance  immediately  prior  to  the purchase of the Option Shares or the
acceptance  of any Stock Repayment Shares but shall include the number of Shares
being  purchased  or  accepted.

                                    ARTICLE 3
                            CLOSING; DELIVERY; NOTICE

     3.1  Initial  Closing.  The  closing  of  the  purchase  and  sale  of  the
Initial  Shares  (the  "Initial  Closing")  shall be held on November 1, 2002 at
10:00  a.m.,  California  time, or within five (5) calendar days of such date as
all applicable consents and approvals of Governmental Authorities required to be
obtained  in  connection  with  the  Transaction  Documents  have been obtained,
including  without  limitation,  the  expiration  or  termination of the HSR Act
waiting  period,  if  any, or on such date Exelixis and GSK may otherwise agree.

     3.2  Payment  and  Delivery  of  the  Initial  Shares.

          3.2.1  Payment.  Subject  to  the  terms  and conditions of this Stock
Purchase  Agreement,  on  the  date  of  the  Initial Closing, GSK shall pay the
purchase  price  of  the  Initial  Shares, as determined pursuant to Section 2.2
hereof,  by  wire  transfer  in  immediately  available  funds to the account of
Exelixis,  in accordance with the wire instructions provided to GSK by Exelixis.

          3.2.2  Delivery.  Subject  to  the  terms and conditions of this Stock
Purchase  Agreement,  on the date of the Initial Closing, Exelixis shall deliver
to  GSK  a  copy  of  the instructions from Exelixis to Exelixis' stock transfer
agent  dated  no  later  than  the  date  of  the Initial Closing, which directs
Exelixis'  transfer  agent  to  prepare  and  deliver to GSK a stock certificate
representing  the Initial Shares as soon as possible, but in no event later than
ten  (10)  Trading  Days  following  the  Initial  Closing.

     3.3  Payment  and  Delivery  of  the  Option  Shares.

          3.3.1  Notice.  Subject  to  the  terms  and  conditions of this Stock
Purchase  Agreement, if Exelixis elects, in its sole discretion, to exercise the
Option,  then  no  later than thirty (30) Trading Days after either (i) the date
GSK selects the Expanded Program Option pursuant to the Development Agreement or
(ii)  the  date  GSK  selects  or is deemed to have selected the Limited Program
Option  pursuant  to  the  Development  Agreement (either such date, the "Option
Exercise  Date"),  Exelixis shall deliver to GSK written notice of such exercise
(the  "Exercise  Notice"),  as  applicable.

          3.3.2  Payment. GSK shall pay the purchase price of the Option Shares,
as  applicable, as determined pursuant to Section 2.2 hereof, on or prior to the
date  which  is  fifteen (15) Trading Days after the date of the Exercise Notice
(an  "Option  Closing Date"). Such purchase price shall be paid by wire transfer
in  immediately  available  funds to the account of Exelixis, in accordance with
the  wire  instructions  provided  to  GSK  by  Exelixis.

          3.3.3  Delivery.  Upon  receipt  of  the  applicable  purchase  price,
Exelixis shall issue instructions, dated not later than the Option Closing Date,
to  Exelixis' stock transfer agent directing Exelixis' transfer agent to prepare
and  deliver  to  GSK  a stock certificate representing the applicable number of
Option  Shares,  as soon as possible, but in no event later than two (2) Trading
Days  following  the  Option  Closing  Date.

     3.4  The  Stock  Repayment  Shares.

          3.4.1  Notice.  Subject  to,  and  in  accordance  with, the terms and
conditions  of this Stock Purchase Agreement and the Loan Agreement, if Exelixis
elects to issue any of the Stock Repayment Shares, Exelixis shall deliver to GSK
written  notice  of  such  election (the "Stock Repayment Notice") no later than
thirty  (30) days prior to a Payment Date (as defined in Section 5.1 of the Loan
Agreement).  Each  Stock  Repayment  Notice  shall set forth the Stock Repayment
Amount  applicable  to  each respective Stock Repayment and the closing date for
such  Stock  Repayment.

          3.4.2 Stock Repayment Closings. Each closing date of a Stock Repayment
shall  be referred to as a "Stock Repayment Closing Date," and together with the
Initial  Closing  and  the Option Closing Date shall be collectively referred to
herein as a "Closing"; provided, however, that each Stock Repayment Closing Date
shall  be  the  applicable Payment Date under Section 5.1 of the Loan Agreement,
unless  the  Parties  otherwise  mutually  agree.

          3.4.3 Delivery; Satisfaction of Obligation. At least three (3) Trading
Days  in  advance  of  any  Stock  Repayment  Closing Date, Exelixis shall issue
instructions  as  follows:

               (a)  if  GSK  is  not  a SEC Affiliate of Exelixis, then Exelixis
shall  issue  instructions to Exelixis' stock transfer agent directing Exelixis'
transfer  agent  to  prepare  and  deliver to the account of GSK by an automated
share transfer through the Depository Trust Company system ("DWAC"), that number
of  shares  of  Exelixis  representing  the applicable Stock Repayment Shares no
later  than  the  Stock  Repayment  Closing  Date;  or

               (b)  if  GSK  is a SEC Affiliate of Exelixis as of the applicable
Stock  Repayment  Closing  Date,  then  Exelixis  shall  issue  instructions  to
Exelixis'  stock  transfer  agent,  directing  the transfer agent to prepare and
deliver  to  Exelixis  a  stock  certificate  evidencing  that  number of shares
representing  the applicable Stock Repayment Shares, as soon as possible, but in
no  event later than one (1) Trading Day prior to the applicable Stock Repayment
Closing  Date,  which stock certificate shall be delivered by Exelixis to GSK on
the applicable Stock Repayment Closing Date; provided however, that Exelixis may
only  issue  Stock  Repayment  Shares in accordance with Section 5.6 of the Loan
Agreement.

               (c)  Subject  to  GSK's  receipt of the stock certificate or DWAC
transfer,  as  the  case may be, for the Stock Repayment Shares, the outstanding
Obligations  (as  defined in the Loan Agreement) due under the terms of the Loan
Agreement  prior to such Stock Repayment shall be deemed repaid to the extent of
the  applicable  Stock  Repayment  Amount.

     3.5  Location.  Each  Closing  shall  be  held  at  the  principal  offices
of  Cooley  Godward  LLP, 3175 Hanover Street, Palo Alto, California, or at such
other  place  as  Exelixis  and  GSK  may  agree.

                                    ARTICLE 4
                   REPRESENTATIONS AND WARRANTIES OF EXELIXIS

     Exelixis  hereby  represents  and warrants to GSK as of the Effective Date,
the  Initial  Closing, the Option Closing Date and Stock Repayment Closing Date,
as  applicable,  as  follows:

     4.1  Organization,  Good  Standings  and  Qualification.  Exelixis:

               (a) is a corporation duly organized, validly existing, authorized
to  exercise  all  its  corporate  powers,  rights  and  privileges, and in good
standing  under  the  laws  of  the  State  of  Delaware;

               (b) has all requisite corporate power and authority to own, lease
and  operate its properties and to carry on its business as now conducted and as
proposed  to  be  conducted;  and

               (c)  is  duly  qualified  as  a  foreign  corporation and in good
standing  in  each  jurisdiction in which the failure to so qualify would have a
Material  Adverse  Effect.

     4.2  Authorization;  Due  Execution.  Exelixis  has  the  requisite
corporate  power  and  authority  to enter into the Transaction Documents and to
perform  its  obligations  under  the  terms  of the Transaction Documents.  All
corporate  action  on  the  part  of  Exelixis,  its  officers,  directors  and
stockholders  necessary  for  the  authorization,  execution and delivery of the
Transaction  Documents  has  been taken.  This Stock Purchase Agreement has been
and  shall  be duly authorized, executed and delivered by Exelixis and, upon due
execution  and delivery by GSK of this Stock Purchase Agreement, will be a valid
and  binding  agreement  of  Exelixis, enforceable in accordance with its terms,
except  as  enforceability  may  be  limited  by  bankruptcy,  insolvency,
reorganization, moratorium or similar laws affecting creditors' rights generally
or  by  equitable  principles.

     4.3  Capital  Stock.  At  September  30, 2002, the authorized capital stock
of Exelixis consisted of 100,000,000 shares of Common Stock, of which 57,196,682
shares  were  outstanding,  and 10,000,000 shares of preferred stock, $0.001 par
value  per  share,  of  which  no shares were outstanding.  Except for shares of
capital  stock  issued  pursuant to employee benefit plans, no shares of capital
stock  of  Exelixis  have been issued, other than as reported in the most recent
SEC Filing which includes information regarding Exelixis' capital stock.  All of
the outstanding shares of Exelixis' capital stock are validly issued, fully paid
and  nonassessable and were issued in compliance with all applicable federal and
state securities laws. Except as set forth in the SEC Filings, as defined below,
and  in  the Transaction Documents, Exelixis has not agreed to register the sale
of  any of its securities under the Securities Act, and there are no outstanding
subscriptions,  options,  warrants,  calls,  contracts,  demands,  commitments,
conversion rights or other agreements or arrangements of any character or nature
whatever  under which Exelixis is or may be obligated to issue its Common Stock,
preferred  stock  or  warrants  or options to purchase Common Stock or preferred
stock.  Except  as  set  forth  in the SEC Filings, no holder of any security of
Exelixis  is  entitled  to  any  rights  of first refusal, preemptive or similar
rights  to  purchase  any securities of Exelixis (including, without limitation,
the  Shares).  In  the  event  GSK's beneficial ownership of Exelixis' shares of
Common Stock exceeds five percent (5%), Exelixis represents and warrants, except
as  otherwise disclosed on Schedule 4.3, there are no outstanding subscriptions,
options,  warrants,  calls,  contracts,  demands,  commitments,  convertible
securities, proxy or stockholder agreements, or other agreements or arrangements
of  any  character  or nature whatever, other than in connection with this Stock
Purchase  Agreement,  pursuant  to  which  Exelixis  is  obligated  to issue any
securities  of  any  kind representing an ownership interest in it.  Neither the
offer  nor  the  issuance  or  sale of the Shares constitutes an event under any
anti-dilution  provisions  of  any  securities  issued  (or issuable pursuant to
outstanding  rights,  warrants  or  options)  by Exelixis or any agreements with
respect  to  the  issuance of securities by Exelixis, which will either increase
the  number  of  securities issuable pursuant to such provisions or decrease the
consideration  per share to be received by Exelixis pursuant to such provisions.

     4.4  Validity  of  Shares.  The  Shares, when issued, sold and delivered in
accordance with the terms of, and for the consideration set forth in, this Stock
Purchase Agreement, shall be duly authorized and validly issued and outstanding,
fully  paid,  nonassessable,  and  free  and  clear  of  all  pledges,  liens,
encumbrances  and restrictions other than the restrictions on transfer set forth
in  Sections  5.3  and  7.4.

     4.5  SEC  Filings;  Financial  Statements.

          4.5.1 SEC Filings. Exelixis has timely filed with the SEC all reports,
registration statements and other documents required to be filed by it (the "SEC
Filings")  under  the Securities Act and the Exchange Act.  The SEC Filings were
prepared  in  accordance  and,  as of the date on which each such SEC Filing was
filed  with  the  SEC,  complied  in  all  material respects with the applicable
requirements  of the Securities Act, the Exchange Act, or the Sarbanes-Oxley Act
of  2002,  as  the  case  may  be.  None of such SEC Filings, including, without
limitation,  any  Financial  Statements, exhibits and schedules included therein
and  documents  incorporated  therein  by reference, at the time filed, declared
effective  or  mailed,  as  the  case may be, contained an untrue statement of a
material  fact or omitted to state a material fact required to be stated therein
or  necessary  in  order  to  make  the  statements  therein,  in  light  of the
circumstances  under which they were made, not misleading.  Except to the extent
information  contained  in any of the SEC Filings has been revised, corrected or
superseded  by any Exelixis' press releases provided to GSK or a later filing of
any such form, report or document, none of the SEC Filings currently contains an
untrue  statement  of a material fact or omits to state a material fact required
to  be  stated  therein or necessary in order to make the statements therein, in
light  of  the  circumstances  under  which  they  were  made,  not  misleading.

          4.5.2  Financial  Statements.  Each  of  the  financial  statements
(including,  in  each case, any notes, exhibits and schedules thereto) contained
in  the  SEC  Filings  was prepared (i) in the case of Forms 10-Q, in accordance
with  United  States  generally accepted accounting principles as promulgated by
the  SEC under Regulation S-X (ii) in the case of Forms 10-K, in accordance with
United  States  generally  accepted  accounting  principles,  including  those
promulgated  by  the SEC under Regulation S-X, with such principles applied on a
consistent  basis  throughout the periods indicated and (iii) in the case of any
other  SEC Filing which contains financial statements, in accordance with United
States  generally accepted accounting principles as promulgated by the SEC under
Regulation  S-X (the "Financial Statements"). The Financial Statements comply in
all  material  respects  with  applicable  accounting requirements and rules and
regulations  of  the  SEC,  and  each  fairly  presented the financial position,
results  of  operations  and changes in the financial position of Exelixis as of
the  respective  dates thereof and for the respective periods indicated therein.

          4.5.3  No  Material  Adverse  Effect. Except as disclosed in Exelixis'
most  recent  SEC  Filings,  specifically  including,  but  not  limited to, the
Financial Statements contained in such SEC Filings, if any, or other information
provided  to  GSK  in  contemplation of the Transaction Documents, there has not
been  (i)  any  Material  Adverse Effect, (ii) other than as contemplated in the
Transaction Documents, any obligation, direct or contingent, that is material to
Exelixis  considered as one enterprise, incurred by Exelixis, except obligations
incurred  in the ordinary course of business, (iii) any dividend or distribution
of any kind declared, paid or made on the capital stock of Exelixis, or (iv) any
loss  or  damage  (whether  or not insured) to the physical property of Exelixis
which  has  been  sustained  which  has  a  Material  Adverse  Effect.

     4.6  Litigation.  Other  than  as  described  in  the  SEC  Filings,  there
are  no  material  Legal  Proceedings  pending  or,  to  Exelixis'  knowledge,
threatened;  nor,  except  as  disclosed  on  Schedule 4.6, are there any formal
inquiries  or  notices  which  may  lead  to  the  institution  of  such  Legal
Proceedings,  against  Exelixis  or its properties, assets or business, which if
adversely  decided,  would,  individually  or  in the aggregate, have a Material
Adverse  Effect  or prevent or adversely affect the transactions contemplated by
this  Stock  Purchase  Agreement.

     4.7  Governmental  Consents.  No  consent,  approval,  order  or
authorization  of,  or  registration, qualification, designation, declaration or
filing  with,  any federal, state, local or provincial governmental authority on
the  part  of  Exelixis  is  required in connection with the consummation of the
transactions  contemplated  by  this  Stock  Purchase Agreement, except for such
approvals or consents required under the HSR Act, if any, and such other notices
required  or  permitted  to  be  filed with certain state and federal securities
commissions  after  the  Effective Date, which notices will be filed on a timely
basis.

     4.8  Compliance  with  Applicable  Laws  and Other Instruments. Exelixis is
not  in  violation  of  or  default  under its Operating Documents or, except as
disclosed  in  the SEC Filings, of any Material Agreement to which it is a party
or  by  which  it  is  bound,  or  to  its  knowledge or to the knowledge of its
executive  officers,  of any provision of federal or state law, or any judgment,
order,  writ,  decree,  statute,  rule or regulation applicable to Exelixis, the
violation  of  which,  with  respect to each of the  above clauses, would have a
Material  Adverse  Effect.  Neither  the  execution  or  delivery  of,  nor  the
performance of or compliance with this Stock Purchase Agreement, the issuance of
the  Shares  nor the consummation of the transactions contemplated by this Stock
Purchase  Agreement  will,  with  or  without the giving of notice or passage of
time,  result  in any breach of, or constitute a default under, or result in the
imposition  of  any  lien  or encumbrance upon any asset or property of Exelixis
pursuant  to, any Material Agreement to which Exelixis is a party or by which it
or  any  of  its  properties,  assets  or  rights is bound or affected or to its
knowledge  any  provision  of federal or state law or any judgment, order, writ,
decree,  statute,  rule  or  regulation  applicable to Exelixis the violation of
which  would  have a Material Adverse Effect, and will not violate the Exelixis'
Operating  Documents.

     4.9  Compliance  with  Environmental  Laws.  Except as disclosed in the SEC
Filings,  Exelixis  is  not,  to  its  knowledge, in violation of any applicable
statute,  law  or  regulation relating to the environment or occupational health
and  safety  which  would  have  a  Material  Adverse  Effect,  and  no material
expenditures  are  or will be required in order to comply with any such existing
statute,  law  or  regulation.  To  its  knowledge,  Exelixis  does not have any
material  liability  to  any Governmental Authority or other Third Party arising
under  or  as  a result of any such past or existing statute, law or regulation.

     4.10  Taxes.  Exelixis,  and its majority-owned subsidiaries have filed all
necessary  federal,  state and foreign income and franchise tax returns and have
paid or accrued all taxes shown as due thereon, and Exelixis has no knowledge of
any  tax deficiency which has been or might be asserted or threatened against it
or  its  majority-owned subsidiaries which would have a Material Adverse Effect.

     4.11  Insurance.  Exelixis,  and  its  majority-owned subsidiaries maintain
insurance  of  the  types  and  in the amounts generally deemed adequate for its
business,  including,  but  not  limited  to,  insurance  covering  all real and
personal  property  owned  or  leased  by  Exelixis  and  its  majority-owned
subsidiaries against theft, damage, destruction, acts of vandalism and all other
risks  customarily  insured against, all of which insurance is in full force and
effect.

     4.12  Properties.  Exelixis  has  good  and  marketable title to all of the
properties and assets reflected as owned in the Financial Statements included in
the  SEC  Filings,  and  such properties and assets are not subject to any lien,
mortgage,  pledge,  charge  or encumbrance of any kind except (i) those, if any,
reflected  in such Financial Statements, or (ii) those which are not material in
amount  and do not adversely affect the use made and promised to be made of such
property  by  Exelixis.  Exelixis  holds  its  leased properties under valid and
binding  leases,  with  such  exceptions  as  are  not materially significant in
relation  to  the business of Exelixis.  Except as disclosed in the SEC Filings,
Exelixis  owns  or leases all such properties as are necessary to its operations
as  now  conducted  or  as  proposed  to  be  conducted.

     4.13  Intellectual  Property.  To the best of the knowledge of Exelixis and
its  majority-owned  subsidiaries  (other  than  Artemis  Pharmaceuticals GmbH),
respectively, Exelixis, and such majority-owned subsidiaries (other than Artemis
Pharmaceuticals  GmbH): (i) own, or have obtained licenses or rights to use, all
of  the  Intellectual  Property  necessary  to  carry  out  Exelixis'  and  its
majority-owned subsidiaries (other than Artemis Pharmaceuticals GmbH) respective
businesses  as  currently  conducted  or as Exelixis contemplates conducting its
business  from time to time in the future and as contemplated by the Transaction
Documents;  (ii)  are  not aware of any notice asserting any ownership rights to
the  Intellectual  Property;  (iii)  are not aware of sales of any products that
would  constitute an infringement by Third Parties of the Intellectual Property;
(iv)  are aware of no pending or threatened action, suit, proceeding or claim by
a  Third  Party  challenging  the ownership rights in, validity or scope of, the
Intellectual  Property;  and  (v)  are  not  aware  of any pending or threatened
action,  suit,  proceeding  or claim by a Third Party asserting that Exelixis or
its  majority-owned  subsidiaries  (other  than  Artemis  Pharmaceuticals  GmbH)
infringe  or otherwise violate any patent, trademark, copyright, trade secret or
other  proprietary  right  of any Third Party as would reasonably be expected to
result  in  a  Material  Adverse  Effect.

     4.14 Effect of Representations and Warranties. None of the representations,
warranties  or  statements  made  to  GSK  in the Stock Purchase Agreement or in
connection  with  the Stock Purchase Agreement contain any untrue statement of a
material  fact,  or omit to state a material fact necessary in order to make the
statements  made  not  misleading.

                                    ARTICLE 5
                     REPRESENTATIONS AND WARRANTIES OF GSK;
                     RESTRICTIONS ON TRANSFER OF THE SHARES

     5.1  Representations  and  Warranties.  GSK  hereby  represents  and
warrants  to Exelixis, as of the Effective Date, the Initial Closing, the Option
Closing  Date  and  Stock  Repayment  Closing  Date,  as applicable, as follows:

          5.1.1  Corporate Organization and Authority. GSK is a corporation duly
organized,  validly  existing,  authorized to exercise all its corporate powers,
rights  and  privileges,  and  in  good standing under the laws of Pennsylvania.

          5.1.2  Authorization;  Due  Execution. GSK has the requisite corporate
power  and  authority  to  enter  into  this  Stock  Purchase  Agreement and the
Transaction  Documents  and  to  perform its obligations under the terms of this
Stock  Purchase  Agreement  and  the  other Transaction Documents. All corporate
action  on  the  part of GSK, its officers, directors and stockholders necessary
for  the  authorization, execution and delivery of this Stock Purchase Agreement
and  the Transaction Documents has been taken. This Stock Purchase Agreement has
been  and  shall be duly authorized, executed and delivered by GSK and, upon due
execution  and  delivery by Exelixis of this Stock Purchase Agreement shall be a
valid  and  binding  agreement of GSK, enforceable in accordance with its terms,
except  as  enforceability  may  be  limited  by  bankruptcy,  insolvency,
reorganization, moratorium or similar laws affecting creditors' rights generally
or  by  equitable  principles.

          5.1.3  Investment Only. This Stock Purchase Agreement is made with GSK
in  reliance  upon  its representations to Exelixis, which by GSK's execution of
this  Stock  Purchase  Agreement  GSK  hereby  confirms,  that  the Shares to be
received by GSK shall be acquired for investment for GSK's own account, not as a
nominee  or  agent,  and not with a view to the sale or distribution of any part
thereof,  and  that GSK does not have any present intention of selling, granting
any participation in or otherwise distributing the same. By executing this Stock
Purchase Agreement, GSK further represents that it has no contract, undertaking,
agreement  or  arrangement  with  any  Person  to  sell,  transfer  or  grant
participation  to such Person or to any third Person, with respect to any of the
Shares.

          5.1.4  Experience.  GSK represents that it: (i) has such knowledge and
experience  in financial and business matters as to be capable of evaluating the
merits  and risks of its prospective investment in the Shares; (ii) has received
all  the  information  it has requested from Exelixis and considers necessary or
appropriate  for  deciding  whether  to  purchase  the Shares; (iii) has had the
opportunity  to  discuss  Exelixis'  business  and  financial  affairs  with its
management;  (iv)  has the ability to bear the economic risks of its prospective
investment;  and  (v)  is  able,  without  materially  impairing  its  financial
condition,  to  hold the Shares for an indefinite period of time and to suffer a
complete  loss  on  its  investment.

          5.1.5  Accredited  Purchaser.  GSK certifies that it presently is, and
shall  as of the Effective Date, the Initial Closing, the Option Closing Date or
Stock Repayment Closing Date, as applicable, be, an "accredited investor" within
the  meaning  of Regulation D of the rules and regulations promulgated under the
Securities  Act.

     5.2  No  Registration.  GSK  understands  that  the  Shares,  other  than
the Stock Repayment Shares, have not been registered under the Securities Act on
the  grounds  that  the  offer and sale of securities contemplated by this Stock
Purchase  Agreement are exempt from registration pursuant to Section 4(2) of the
Securities  Act,  and  that Exelixis' reliance upon such exemption is predicated
upon  GSK's  representations  set  forth  in  this  Stock  Purchase  Agreement.

     5.3  Limitations  on  Transfer.  GSK  covenants  that,  subject  to  other
restrictions  on  transfer set forth elsewhere in this Stock Purchase Agreement,
in  no  event shall it dispose of any of the Shares (other than pursuant to Rule
144  promulgated by the SEC under the Securities Act ("Rule 144") or any similar
or analogous rule), unless and until (a) GSK shall have notified Exelixis of the
proposed disposition, and (b) if requested by Exelixis, GSK shall have furnished
Exelixis  with  an  opinion  of  counsel  reasonably  satisfactory  in  form and
substance to Exelixis and Exelixis' counsel, in the reasonable exercise of their
judgment, to the effect that (i) such disposition shall not require registration
under  the  Securities  Act and (ii) appropriate action necessary for compliance
with  the Securities Act and any applicable state, local or foreign law has been
taken.  Notwithstanding  the  foregoing, GSK may sell the Stock Repayment Shares
at  any  time  and  may  transfer  any  Shares  to  a  Permitted  Transferee.

     5.4  Legend.  Each  certificate  representing  the  Shares,  other than the
Stock  Repayment  Shares,  shall  be  endorsed  with substantially the following
legends:
     (i)  THE  SECURITIES EVIDENCED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
     UNDER  THE  SECURITIES  ACT  OF  1933,  AS  AMENDED,  AND  MAY NOT BE SOLD,
     TRANSFERRED OR ASSIGNED UNLESS THERE IS AN EFFECTIVE REGISTRATION STATEMENT
     UNDER SUCH ACT COVERING SUCH SECURITIES, THE TRANSFER IS MADE IN COMPLIANCE
     WITH  RULE  144  PROMULGATED  UNDER  SUCH  ACT,  OR THE COMPANY RECEIVES AN
     OPINION OF COUNSEL REASONABLY SATISFACTORY TO THE COMPANY STATING THAT SUCH
     SALE,  TRANSFER  OR ASSIGNMENT IS EXEMPT FROM THE REGISTRATION AND DELIVERY
     REQUIREMENTS  OF  SUCH  ACT;  and

     (ii)  THE SECURITIES EVIDENCED BY THIS CERTIFICATE ARE SUBJECT TO A LOCK-UP
     AGREEMENT  AND  MAY  NOT  BE  SOLD,  TRANSFERRED  OR ASSIGNED OTHER THAN IN
     ACCORDANCE WITH THE TERMS OF THAT CERTAIN STOCK PURCHASE AND STOCK ISSUANCE
     AGREEMENT, DATED OCTOBER 28, 2002, WITHOUT THE PRIOR WRITTEN CONSENT OF THE
     COMPANY;  and

     (iii)  ANY  LEGEND  REQUIRED  TO  BE PLACED ON THE STOCK CERTIFICATES UNDER
     APPLICABLE  STATE  SECURITIES  LAWS.

                                    ARTICLE 6
                              CONDITIONS TO CLOSING

     6.1  Conditions  to  Obligations  of  GSK  to  Consummate  each  Closing.
The obligation of GSK to consummate each Closing and to purchase and pay for, or
otherwise  accept, as applicable, the Shares being issued pursuant to this Stock
Purchase  Agreement  is subject to the satisfaction or GSK's waiver, on or prior
to  each  Closing,  of  each  of  the  following  conditions,  as  applicable:

          6.1.1 Exelixis' representations and warranties contained in this Stock
Purchase  Agreement,  as  updated  by Exelixis' most recent SEC Filings, are and
will  be  true and correct as of the date of the Initial Closing and each of the
Option  Closing Dates or Stock Repayment Closing Dates, as applicable, as though
made  on  and  as  of  that  date.

          6.1.2  An  officer's certificate executed by Exelixis' Chief Executive
Officer  or  Chief  Financial  Officer  shall  have  been  delivered to GSK (the
"Officer's  Certificate") in the form attached hereto as Exhibit "A" certifying,
among  other  things,  that the representations and warranties contained in this
Stock Purchase Agreement are true and correct as of the Closing Date and that no
events  which  had a Material Adverse Effect, occurred during the period used to
calculate  the  purchase  price  of  the  Shares  subject  to  the  Closing.

          6.1.3 The Transaction Documents shall have been executed and delivered
by  Exelixis.

          6.1.4  Exelixis  and  GSK shall have obtained all consents (including,
without limitation, the expiration or termination of the HSR Act waiting period,
if any, and all governmental or regulatory consents, approvals or authorizations
required  in  connection  with  the  valid  execution and delivery of this Stock
Purchase  Agreement  or any Closing hereunder), permits and waivers necessary or
appropriate  for  consummation  of  the  transactions contemplated by this Stock
Purchase  Agreement.

          6.1.5  No  Governmental  Authority  shall  have  enacted,  issued,
promulgated,  enforced  or  entered  any law, rule, regulation, executive order,
decree,  injunction or other order which is then in effect and has the effect of
making  illegal  the purchase of, or payment for, the Shares by GSK or otherwise
preventing  the  consummation of any of the transactions contemplated under this
Stock  Purchase  Agreement.

          6.1.6  There  shall  be  no  Legal  Proceeding  challenging this Stock
Purchase  Agreement  or  the  transactions  contemplated  by this Stock Purchase
Agreement,  or  seeking  to  prevent  or  delay the consummation of any Closing,
instituted  and  pending  before  any  court  or  Government  Authority.

          6.1.7  The  Common  Stock  of Exelixis shall be trading or listed on a
National  Securities  Market.

          6.1.8  Exelixis shall not be insolvent, filed a petition for voluntary
bankruptcy  or  have become the subject of an involuntary bankruptcy proceeding,
made  an  assignment  for  the  benefit  of  creditors,  been  voluntarily  or
involuntarily  dissolved  or  has had a receiver, trustee or other court officer
appointed  for  its  property.

          6.1.9  A  Change  of  Control  shall not have occurred as described in
Section  13.1  of  the  Development  Agreement.

          6.1.10  All  Stock  Repayment Shares issued to GSK pursuant to Section
2.4  of  this  Stock  Purchase  Agreement  shall  have been registered under the
Securities  Act  on  any SEC registration statement form used to register shares
that  Exelixis  is  eligible  to  use  prior  to  GSK's acceptance of such Stock
Repayment  Shares and shall be immediately available for transfer or disposal by
GSK,  subject to GSK not being deemed a SEC Affiliate of Exelixis, in which case
the  stock  certificates  shall  contain  appropriate  legends.

          6.1.11 GSK shall have received an opinion of Cooley Godward LLP, dated
as of the date of the Initial Closing or an applicable Closing, in substantially
the  form  attached  hereto  as  Exhibit  "B".

          6.1.12  Exelixis  shall  have  promptly delivered to GSK copies of any
amendments  or  modifications  to  its  Operating  Documents  certified  by  the
Secretary  of  State of Delaware, and, with respect to the bylaws, the Secretary
of  Exelixis.

          6.1.13  With  respect  to  the Stock Repayment Shares, the Development
Agreement  shall  not  have  been terminated by GSK pursuant to Sections 12.2.1,
12.3.1  or  12.4  of  the  Development  Agreement.

          6.1.14  There  shall  not  have occurred a Material Breach by Exelixis
that  has  not been cured in accordance with the provisions of Section 12.2.1 of
the  Development  Agreement.

     6.2  Conditions  to  Obligations  of  Exelixis  to  Consummate  each
Closing.  The obligations of Exelixis to consummate each Closing and to sell and
issue the Shares is subject to the satisfaction or Exelixis' waiver, on or prior
to  each  Closing,  of  each  of  the  following  conditions,  as  applicable:

          6.2.1  GSK's  representations  and  warranties contained in this Stock
Purchase  Agreement  are  true and correct as of the date of the Initial Closing
and  each  of  the  Option  Closing  Dates  or Stock Repayment Closing Dates, as
applicable,  as  though  made  on  and  as  of  that  date.

          6.2.2 The Transaction Documents shall have been executed and delivered
by  GSK.

          6.2.3  Exelixis  and  GSK  shall have obtained all consents (including
without limitation, the expiration or termination of the HSR Act waiting period,
if any, and all governmental or regulatory consents, approvals or authorizations
required  in  connection  with  the  valid  execution and delivery of this Stock
Purchase  Agreement  or any Closing hereunder), permits and waivers necessary or
appropriate  for  consummation of the transactions contemplated under this Stock
Purchase  Agreement.

          6.2.4  No  Governmental  Authority  shall  have  enacted,  issued,
promulgated,  enforced,  or  entered any law, rule, regulation, executive order,
decree,  injunction or other order which is then in effect and has the effect of
making  illegal  the purchase of, or payment for, the Shares by GSK or otherwise
preventing  the  consummation of any of the transactions contemplated under this
Stock  Purchase  Agreement.

          6.2.5  There  shall  be  no  Legal  Proceeding  challenging this Stock
Purchase  Agreement  or  the  transactions  contemplated  by this Stock Purchase
Agreement,  or  seeking  to  prevent  or  delay the consummation of any Closing,
instituted  and  pending  before  any  court  or  Government  Authority.

                                    ARTICLE 7
                   ADDITIONAL AGREEMENTS; LOCK UP; STANDSTILL

     7.1  Registration  of  Shares.

          7.1.1  Registration  Requirements.

               (a)  Required  Registration. In the event that any of the Initial
Shares  or  the Option Shares (the "Registrable Shares") issued pursuant to this
Stock Purchase Agreement have not been held by GSK, or a Permitted Transferee of
GSK,  for  over  one  (1) year (if GSK is not a SEC Affiliate under Rule 144) or
over  two  (2) years (if GSK is a SEC Affiliate under Rule 144), at such time as
they  become available for resale in accordance with the terms and conditions of
Section 7.4 hereof (the "Registration Trigger Date"), Exelixis shall either: (i)
work  diligently  using  its  reasonable  efforts,  and  as  soon  as reasonably
practicable  after  the  Registration  Trigger  Date (but in no event later than
forty-five  (45) days after the Registration Trigger Date), to file with the SEC
a  registration  statement  on  Form  S-3,  covering the Registrable Shares (the
"Resale  Registration  Statement"),  and  shall  secure the effectiveness of the
Resale  Registration  Statement  as soon as reasonably practicable thereafter or
(ii)  for  shares  held  at  least two (2) years, provide GSK with a replacement
stock  certificate  without  legends in a form ready for transfer or disposal or
deliver  the shares to the account of GSK by an automated share transfer through
the  DWAC  in  uncertificated  form  and remove any stop transfer order attached
thereto  in  order  to  ensure  that  such  shares  are  freely  tradable.

               (b)  Effectiveness.  Subject  to Section 7.1.4, Exelixis shall be
obligated to maintain the effectiveness of the Resale Registration Statement and
any  registration  statement  filed in connection with the issuance of the Stock
Repayment Shares (together with the Resale Registration Statement referred to in
this  Section  7.1  as  the  "Registration  Statements")  with the SEC until the
earlier  of  (i)  the sale of all of the Registrable Shares or (ii) the time all
otherwise  unsold  Registrable  Shares  may  be  sold  pursuant  to Rule 144(k).

               (c)  Repurchase.  If  Exelixis  is  unable  to  cause  the Resale
Registration  Statement to become effective within one hundred eighty (180) days
of the Registration Trigger Date, Exelixis, subject to applicable law, shall, if
GSK  so requests in writing not later than ninety (90) days after the expiration
of  such  one hundred eighty (180) day period, purchase from GSK the Registrable
Shares  for  a purchase price equal to GSK's purchase price for such Registrable
Shares.  Such repurchase shall be effected not later than thirty (30) days after
Exelixis'  receipt of GSK's request therefor; provided, however, that if, at any
time  prior  to  the  date  such  repurchase is being effected, such Registrable
Shares  may  be  sold  pursuant  to  Rule  144,  then Exelixis' obligation to so
repurchase  shall  be  of  no  force  and  effect.

          7.1.2  Incidental  Registration.  If Exelixis at any time (but subject
to  Section  7.4  hereof)  proposes  to register any of its securities under the
Securities  Act  for  sale to the public, whether for its own account or for the
account  of  other security holders or both (except with respect to registration
statements  on  Forms  S-4  or S-8 or another form not available for registering
Registrable Shares for sale to the public), each such time it will promptly give
written  notice  of  its intentions to GSK (an "Incidental Registration").  Upon
the  written request of GSK, received by Exelixis within ten (10) days after the
giving  of  any such notice by Exelixis, to register any of its securities which
are  not  yet registered under the Securities Act (which request shall state the
intended  method  of  disposition  thereof),  Exelixis  will  use its reasonable
efforts to cause the Registrable Shares as to which registration shall have been
so  requested to be included in the securities to be covered by the registration
statement  proposed  to  be  filed  by  Exelixis, all to the extent requisite to
permit  the  sale  or  other  disposition by GSK (in accordance with its written
request)  of  such  Registrable  Shares  so  registered.  In  the event that any
registration  pursuant  to  this  Section  shall  be,  in  whole  or in part, an
underwritten  public  offering  of  Common  Stock,  the  number  of  shares  of
Registrable  Shares to be included in such an underwriting may be reduced if and
to  the  extent  that the managing underwriter shall be of the opinion that such
inclusion  would  adversely affect the marketing of the securities to be sold by
Exelixis; and subject to the foregoing, any reduction of the number of shares of
Registrable  Shares  shall  be accomplished by excluding all or a portion of the
shares  proposed  to  be  included  by  holders  of Registrable Shares and other
securities  with  registration  rights  who  have elected to participate in such
registration,  with  such  reduction  in  the  number  of shares in the offering
required  by  the  managing underwriter because of market conditions to be borne
pro-rata  by  all holders of Registrable Shares and other securities who elected
to  participate in such registration, with each holder of Registrable Shares and
other  securities that is participating in the offering sharing the reduction in
the  ratio that the number of shares proposed to be registered by such holder of
Registrable  Shares  or  other securities bears to the total number of shares of
Registrable  Shares or other securities proposed to be registered by all holders
of  Registrable  Shares  or  other  securities.  Notwithstanding  the  foregoing
provisions, Exelixis may withdraw any registration statement referred to in this
Section  7.1.2  without  thereby  incurring  any  liability  to  the  holders of
Registrable  Shares.

          7.1.3  Registration  Expenses.  Exelixis  shall  pay  all Registration
Expenses  (as  defined below) in connection with any registration, qualification
or  compliance  hereunder,  and  GSK  shall pay all Selling Expenses (as defined
below)  that  relate to the Registrable Shares or the Stock Repayment Shares, as
applicable.  "Registration Expenses" shall mean all expenses, except for Selling
Expenses,  incurred  by  Exelixis  in complying with the registration provisions
herein  described,  including,  without  limitation,  all  registration,
qualification,  compliance  and  filing  fees,  printing  expenses,  fees  and
disbursements of counsel for Exelixis, blue sky fees and expenses and accounting
fees (including the expense of any special audits incident to or required by any
such  registration).  "Selling Expenses" shall mean all fees of counsel for GSK,
selling  commissions,  underwriting  fees and stock transfer taxes applicable to
the  Registrable  Shares  or  the  Stock  Repayment  Shares,  as  applicable.

          7.1.4  Registration  Suspension. Exelixis shall, upon (i) the issuance
by  the  SEC  of  a  stop order suspending the effectiveness of the Registration
Statements  or  the  initiation  of proceedings with respect to the Registration
Statements under Section 8(d) or 8(e) of the Securities Act, (ii) the occurrence
of  any  event  or the existence of any fact (a "Material Event") as a result of
which  the  Registration  Statements  or  the  related  preliminary  or  final
prospectuses  shall  contain  any untrue statement of a material fact or omit to
state  any  material fact required to be stated therein or necessary to make the
statements  therein,  in  the  light  of the circumstances under which they were
made,  not  misleading,  or  (iii)  the  occurrence  or existence of any pending
corporate  development  that, in the reasonable discretion of Exelixis, makes it
appropriate  to  suspend the availability of the Registration Statements and the
related  prospectuses:

               (a)  in  the  case  of  clause  (ii) above, subject to the clause
(iii),  as  promptly  as  practicable prepare and file, if necessary pursuant to
applicable  law,  a post-effective amendment to the Registration Statements or a
supplement  to  the related prospectuses or any document incorporated therein by
reference  or  file  any  other  required document that would be incorporated by
reference  into the Registration Statements and the related prospectuses so that
the  Registration  Statements  and  the  related prospectuses do not contain any
untrue  statement of a material fact or omit to state any material fact required
to  be  stated therein or necessary to make the statements therein, in the light
of  the  circumstances under which they were made, not misleading, as thereafter
delivered  to  the  purchasers  of the Registrable Shares or the Stock Repayment
Shares,  as  applicable,  being  sold  thereunder,  and,  in  the  case  of  a
post-effective  amendment  to  the  Registration Statements, subject to the next
sentence,  use  its  reasonable  efforts to cause it to be declared effective as
promptly  as  is  practicable,  and

               (b)  give notice to GSK that the availability of the Registration
Statements  is suspended (a "Deferral Notice") and, upon receipt of any Deferral
Notice,  GSK  agrees  not  to sell any Registrable Shares or the Stock Repayment
Shares,  as  applicable, pursuant to the Registration Statements until such time
as  GSK receives copies of the supplemented or amended prospectuses provided for
in  clause  (a)  above,  or  until it is advised in writing by Exelixis that the
prospectuses  may  be  used,  and  has  received  copies  of  any  additional or
supplemental  filings  that are incorporated or deemed incorporated by reference
in  such  prospectuses. Exelixis shall use all reasonable efforts to ensure that
the  use  of  the prospectuses may be resumed (x) in the case of clauses (i) and
(ii)  above,  as promptly as is practicable, and (y) in the case of clause (iii)
above,  as soon as, in the reasonable judgment of Exelixis, public disclosure of
such  Material Event would not be prejudicial to or contrary to the interests of
Exelixis  or,  if  necessary to avoid unreasonable burden or expense, as soon as
practicable  thereafter.  Exelixis shall be entitled to exercise its right under
this  Section  7.1.4  to  suspend  the  availability of each of the Registration
Statements  or any related prospectuses no more than two (2) times in any twelve
(12)  month  period,  and  any  such period during which the availability of the
Registration Statements and any related prospectuses is suspended (the "Deferral
Period")  shall  not  exceed  thirty  (30) days. The period of any such Deferral
Period  shall  be  added  to  the period of time Exelixis has agreed to keep the
Registration  Statements effective. Exelixis shall use all reasonable efforts to
limit  the  duration  and number of any Deferral Periods. GSK hereby agrees that
upon  receipt  of  any Deferral Notice from Exelixis, GSK shall, and shall cause
each  of  its  officers,  directors, employees, affiliates, advisors, agents and
representatives  to,  keep  confidential  all nonpublic information set forth in
such  notice  including  the  existence  or  terms  of  such  Deferral  Notice.

          7.1.5  Registration  Procedures.  In  the  case  of  any  registration
effected  by Exelixis pursuant to Section 7.1, Exelixis shall use all reasonable
efforts:

               (a)  to  respond  promptly to any comments of the SEC relating to
the  Registration  Statements,  and  to  prepare  and  file  with  the  SEC such
amendments  (including  post-effective  amendments)  and  supplements  to  the
Registration  Statements  and  the  related  prospectuses as may be necessary to
comply with the provisions of the Securities Act with respect to the disposition
of  the Registrable Shares or the Stock Repayment Shares, as applicable, covered
by  the  Registration  Statements;

               (b)  to  furnish such number of Registration Statements and other
documents  incident  thereto,  including  any  amendment of or supplement to the
Registration  Statements  or related prospectuses, as GSK may reasonably request
to  facilitate  the  public  sale  or  other  disposition  of  all or any of the
Registrable  Shares  or  the  Stock  Repayment  Shares,  as  applicable;  and

               (c)  to file the documents required of Exelixis and otherwise use
all  reasonable  efforts  to  register and qualify the Registrable Shares or the
Stock  Repayment  Shares,  as applicable, covered by the Registration Statements
under  such  other securities or blue sky laws of such jurisdictions as shall be
reasonably  appropriate  in  the  opinion  of  Exelixis; provided, however, that
Exelixis  shall  not  be required to qualify to do business or to file a general
consent  to  service of process in any state in which it is not now so qualified
or  has  not  so  consented  except  as  may  be required by the Securities Act.

          7.1.6  Indemnification.

               (a) Indemnification by Exelixis. Exelixis agrees to indemnify and
hold harmless GSK (and its officers, directors, Affiliates and agents), from and
against any and all losses, claims, damages, liabilities or expenses (or actions
or  proceedings  in  respect  thereof)  to  which any of them may become subject
(under the Securities Act or otherwise) insofar as such losses, claims, damages,
liabilities or expenses (or actions or proceedings in respect thereof) arise out
of,  or are based upon (i) any untrue statement or alleged untrue statement of a
material  fact or omission or alleged omission to state a material fact required
to  be  stated  therein or necessary to make the statements therein, in light of
the  circumstances  in which they were made, not misleading, in the Registration
Statements  (on  the  respective  effective  dates  thereof),  or  the  related
prospectuses  and  any amendments or supplements thereto, or (ii) any failure by
Exelixis  to  fulfill  any  undertaking included in the Registration Statements.
Exelixis  shall,  as  incurred, reimburse the indemnified parties herein for any
legal  or  other  expenses  reasonably  incurred  in investigating, defending or
preparing  to defend any such claims, actions or proceedings in respect thereof;
provided,  however, that the indemnity agreement contained in this Section 7.1.6
shall  not  apply to amounts paid in settlement of any such loss, claim, damage,
liability  or  expense,  if  such  settlement is effected without the consent of
Exelixis  (which such consent shall not be unreasonably withheld) and, provided,
further,  that  Exelixis shall not be liable in any such case to the extent that
such  loss,  claim, damage, liability or expense arises out of, or is based upon
(A)  any  untrue  statement or omission of a material fact required to be stated
therein  or  necessary  to  make  the  statements  therein,  in  light  of  the
circumstances  in  which  they  were  made,  not misleading, in the Registration
Statements  (on  the  respective  effective  dates  thereof),  or  the  related
prospectuses  and  any  amendments or supplements thereto, made in reliance upon
and  in  conformity  with  written  information  furnished  to  Exelixis  by GSK
specifically for use in preparation of such document, or (B) an untrue statement
or  omission  in  the  related  prospectuses  and  any amendments or supplements
thereto,  that  is  corrected  in  any  subsequent  prospectus, or supplement or
amendment  thereto,  that  was  delivered to GSK prior to the sale or sales from
which  a  loss  or  liability  arose.

               (b)  Indemnification  by  GSK.  GSK  agrees to indemnify and hold
harmless Exelixis (and its officers, directors, Affiliates and agents), from and
against  any  losses,  claims,  damages,  liabilities or expenses (or actions or
proceedings  in  respect thereof) to which any of them may become subject (under
the  Securities  Act  or  otherwise)  insofar  as  such losses, claims, damages,
liabilities or expenses (or actions or proceedings in respect thereof) arise out
of,  or  are  based  upon  any  untrue  statement or omission of a material fact
required  to  be  stated therein or necessary to make the statements therein, in
light  of  the  circumstances  in  which  they were made, not misleading, in the
Registration  Statements  (on  the  respective  effective dates thereof), or the
related prospectuses and any amendments or supplements thereto, made in reliance
upon  and  in conformity with written information furnished to Exelixis by or on
behalf  of  GSK  specifically for use in preparation of such document; provided,
however, that the indemnity agreement contained in Section 7.1.6 shall not apply
to  amounts  paid  in  settlement  of any such loss, claim, damage, liability or
expense,  if  such settlement is effected without the consent of GSK (which such
consent  shall not be unreasonably withheld) and that GSK shall not be liable in
any  such  case  for  any  (A)  untrue statement or omission in the Registration
Statements  or  the  related  prospectuses  and  any  amendments  or supplements
thereto,  which statement or omission has been corrected, in writing, by GSK and
delivered  to  Exelixis  ten  (10)  days  before  the  sale from which such loss
occurred,  or  (B)  untrue statement or omission in the related prospectuses and
any  amendments  or  supplements  thereto or that is corrected in any subsequent
prospectus,  or  amendment  or supplement thereto, and delivered to GSK prior to
the sale or sales from which a loss or liability arose.  GSK shall, as incurred,
reimburse  the  indemnified  parties  herein  for  any  legal  or other expenses
reasonably  incurred in investigating, defending or preparing to defend any such
claims,  actions  or  proceedings  in  respect  thereof.

               (c)  Indemnification  Procedure.  Promptly  after  receipt by any
indemnified  party  of  a  notice  of  a claim or the beginning of any action in
respect  of  which  indemnity  is  to  be  sought  against an indemnifying party
pursuant  to  this  Section  7.1.6(c),  such  indemnified party shall notify the
indemnifying  party  in  writing  of  such  claim or of the commencement of such
action,  and,  subject  to  the  provisions hereinafter stated, in case any such
action shall have been brought against an indemnified party and the indemnifying
party shall have been notified thereof, the indemnifying party shall be entitled
to  participate  therein,  and,  to the extent that it shall wish, to assume the
defense  of such action, with counsel reasonably satisfactory to the indemnified
party. After notice from the indemnifying party to such indemnified party of the
indemnifying  party's  election  to assume the defense thereof, the indemnifying
party  shall  not  be  liable  to  such indemnified party for any legal expenses
subsequently  incurred  by such indemnified party in connection with the defense
thereof;  provided,  however,  that if there exists or shall exist a conflict of
interest  that  would  make  it  inappropriate in the reasonable judgment of the
indemnified  party  for the same counsel to represent both the indemnified party
and  such  indemnifying  party  or  any  affiliate  or  associate  thereof,  the
indemnified  party shall be entitled to retain its own counsel at the expense of
such  indemnifying  party.  Failure  of any indemnifying party to give notice as
provided  herein  shall  not  relieve  the indemnifying party of its obligations
under  this  Section  7.1.6.  No  indemnifying party, in the defense of any such
claim  or  action,  except  with  the  consent  of each indemnified party, shall
consent  to  entry  of  any  judgment  or  enter  into  any  settlement.

               (d)  Other  Liability.  The obligations of Exelixis and GSK under
Section  7.1  shall  be  in addition to any liability which Exelixis and GSK may
otherwise  have  to  each  other.

     7.2  Filings.  Exelixis  covenants  and  agrees  to  use  all  reasonable
efforts  to:  (i) make and keep public information available, as those terms are
understood  and  defined  in Rule 144, (ii) file with the SEC in a timely manner
all  reports  and  other documents required of Exelixis under the Securities Act
and  Exchange  Act,  and  (iii)  provide GSK, upon written request, with written
assurance  that Exelixis has made and kept such public information available and
has  timely filed all reports and other documents required of Exelixis under the
Securities  Act  and  Exchange  Act.

     7.3  Other  Actions.  Upon  the  terms  and  subject  to  the  conditions
hereof,  each  of the Parties hereto shall in good faith, use reasonable efforts
to take, or cause to be taken, all appropriate action, and to do, or cause to be
done,  all  things  necessary,  proper  or  advisable  under applicable laws and
regulations  to consummate and make effective the transaction contemplated under
this  Stock  Purchase Agreement, including, without limitation, using reasonable
efforts  to  obtain  all licenses, permits, consents, approvals, authorizations,
qualifications  and  orders of Governmental Authorities and parties to contracts
with  Exelixis  as  are necessary for the execution, delivery and performance of
this  Stock  Purchase  Agreement.

     7.4  Lock  Up  and  Selling  Restrictions.

          7.4.1  Subject  to  Section  7.9,  GSK agrees that for a period of [*]
following  the  date  of the Initial Closing or [*] following the Option Closing
Date,  as  applicable,  (the  "Restricted  Period"), neither GSK, nor any of its
Affiliates,  shall  offer,  sell,  contract  to sell, pledge, grant an option to
purchase, make a short sale or otherwise dispose of any Initial Shares or Option
Shares  held by GSK or any of its Affiliates, or grant an option or other rights
to  any Person to acquire any Initial Shares or Option Shares, without the prior
written  consent  of  Exelixis.

          7.4.2  GSK  agrees  that in each full calendar year from and after the
earlier  to  occur  of  (i)  the expiration of the Restricted Period or (ii) [*]
(either  such date, the "Limited Release Date"), GSK and/or its Affiliates shall
not  offer,  sell, contract to sell, pledge, grant an option to purchase, make a
short  sale  or otherwise dispose of greater than [*] of the total number of any
Initial  Shares  and  Option  Shares  purchased  by  GSK  pursuant to this Stock
Purchase  Agreement.  For  periods after the Limited Release Date of less than a
full calendar year, GSK shall be permitted to dispose of that pro-rata number of
Initial Shares and Option Shares which shall be determined by multiplying [*] of
the  total  number  of  Initial  Shares and Option Shares, purchased by GSK by a
fraction, the numerator of which is total number of days in that given year from
the  Limited  Release Date to the last calendar day in such year and denominator
of which is three hundred and sixty-five (365). The restrictions imposed by this
Section  7.4.2  shall  terminate  on  [*],  subject  to  extension by [*] if the
Restricted  Period  is  extended pursuant to the provisions set forth in Section
7.4.4  of  this  Stock  Purchase  Agreement.

          7.4.3  During the Restricted Period, the consent of Exelixis shall not
be  required  for  the transfers by GSK of all or a portion of the Shares to its
Affiliates  (a  "Permitted  Transferee"); provided, however, that such Affiliate
agrees to become a party to, and be bound by, all of the terms and conditions of
this  Stock  Purchase  Agreement by duly executing and delivering to Exelixis an
Instrument  of  Adherence  in  the  form  attached  as  Exhibit  "C"  hereto.

          7.4.4  Notwithstanding  anything  to  the  contrary  contained in this
Section  7.4  or  Section  7.9  hereof,  in  the  event  of  termination  of the
Development  Agreement  by  either:  (A)  GSK  pursuant to Section 12.3.2 of the
Development  Agreement;  or  (B)  Exelixis (i) pursuant to Section 12.2.1 of the
Development  Agreement upon Material Breach by GSK; or, (ii) pursuant to Section
12.4  of  the  Development Agreement upon the insolvency of GSK, as set forth in
Section  12.6.4  of  the Development Agreement, in each of clause (A), (B)(i) or
(B)(ii),  the  Restricted Period shall be extended for a period of [*] following
the  effective  date  of  such  termination  by  GSK or Exelixis, as applicable.

     7.5  Standstill.  Subject  to  Section  7.6,  prior to [*] (the "Standstill
Period"),  neither  GSK nor any of its Affiliates shall, in any manner, directly
or  indirectly, except as agreed by Exelixis in writing or as provided expressly
under  this  Stock  Purchase  Agreement:

          7.5.1  make, effect, initiate, cause or participate in any acquisition
of  beneficial  ownership  of  any  securities  or any assets of Exelixis or any
securities  or  any  assets  of any Exelixis' majority-owned subsidiaries or any
other  Affiliate  of  Exelixis;

          7.5.2  form,  join  or  participate  in  a  "group" (as defined in the
Exchange  Act)  with  respect  to  the beneficial ownership of any securities of
Exelixis;

          7.5.3  agree  or  offer  to take, or encourage or propose (publicly or
otherwise) the taking of any action referred to in subsections 7.5.1 or 7.5.2 of
this  Section  7.5;  or

          7.5.4  assist, induce or encourage any other Person to take any action
of  the  type  referred  to in subsections 7.5.1, 7.5.2 or 7.5.3 of this Section
7.5.

     7.6  Conditions  Eliminating  Standstill.  Notwithstanding  the
restrictions  set  forth  in  Section  7.5,  the  obligations  of GSK during the
Standstill  Period  as set forth in Section 7.5 shall not apply and will have no
force  or  effect  under  the  following  circumstances; provided, however, that
neither  GSK,  nor any of it Affiliates, shall take any action that would impair
GSK's  obligations  to purchase, or otherwise accept, the Shares under the terms
of  this  Stock  Purchase  Agreement:  [*]

     7.7  Conditions  Eliminating  Lock  Up.  Notwithstanding  the  restrictions
set  forth in Section 7.4.1, the obligations of GSK during the Restricted Period
as  set  forth in Section 7.4.1 shall not apply and will have no force or effect
under  the  following  circumstances:  [*]

     7.8  Use  of  Proceeds.  Exelixis  shall  use  the  proceeds  received
from  the  issuance  of the Shares for the funding of activities contemplated in
the  Development  Agreement  over  the  course  of  its  term.

     7.9          Exelixis  Repurchase  Option.  In  the event of termination of
the  Development  Agreement  by either (A) GSK pursuant to Section 12.3.2 of the
Development  Agreement  or  (B)  Exelixis  pursuant  to  Section  12.2.1  of the
Development Agreement upon Material Breach by GSK or pursuant to Section 12.4 of
the  Development  Agreement upon the insolvency of GSK,  as set forth in Section
12.6.4  of the Development Agreement, Exelixis shall have the right, but not the
obligation,  subject to applicable law, to repurchase from GSK, for a [*] period
following notice by the terminating Party that it is terminating the Development
Agreement,  any or all of the Initial Shares or Option Shares held by GSK at the
time  of  such  termination  as  follows:

          7.9.1 In the event of termination by GSK pursuant to Section 12.3.2 of
the  Development  Agreement,  then  Exelixis  may  repurchase  any or all of the
Initial  Shares  or Option Shares then held by GSK at a price per share equal to
[*],  as  applicable.

          7.9.2  In  the  event  of  termination by Exelixis pursuant to Section
12.2.1  of the Development Agreement upon Material Breach by GSK or Section 12.4
of  the Development Agreement upon GSK's insolvency, then in accordance with the
provisions  set  forth  in Section 12.6.4 of the Development Agreement, Exelixis
may  repurchase  any  or all of the Initial Shares or Option Shares then held by
GSK  at  a  price  per share equal to [*] of the Repurchase Market Value of such
shares  as  of  the  effective  date of such termination. The "Repurchase Market
Value"  of the Common Stock shall be deemed to be the average of the opening and
closing  sale  prices of the Common Stock as reported by the National Securities
Market  on  which  the  Common Stock trades or is listed for the [*] consecutive
Trading  Days  immediately  preceding  and  the  [*]  consecutive  Trading  Days
immediately  following  the  effective  date  of termination of such Development
Agreement.

          7.9.3  Exelixis  shall give GSK a written notice, of not less than [*]
Trading  Days,  of  its intent to effect a repurchase pursuant to either Section
7.9.1  or  Section  7.9.2, which notice shall specify the number of shares being
repurchased, the aggregate repurchase price determined and payable in accordance
with  the  terms set forth in Section 7.9.1 or Section 7.9.2, as applicable, and
the  time,  place and date for settlement of such repurchase. On such settlement
date,  Exelixis  shall  deliver to GSK the repurchase price for the shares being
repurchased  in  accordance with the terms set forth in Section 7.9.1 or Section
7.9.2,  as  applicable,  and  GSK  shall  surrender  to  Exelixis  the  stock
certificate(s)  or other evidence representing such shares. Upon delivery of the
notice  and  payment  of  the  repurchase  price pursuant to this Section 7.9.3,
Exelixis  shall  become  the  legal  and  beneficial  owner  of the shares being
repurchased and all rights and interest therein or related thereto, and Exelixis
shall  have  the right to transfer to its own name the shares being repurchased.

                                    ARTICLE 8
                                  MISCELLANEOUS

     8.1  Publicity.  Neither  Party  shall  originate  any  written
publicity,  news  release  or  other  announcement  or statement relating to the
announcement or terms of this Stock Purchase Agreement except in compliance with
the  provisions  set  forth  in  Section  14.1  of  the  Development  Agreement.
Notwithstanding anything to the contrary set forth above, the provisions of this
Section  8.1  shall  not  apply  to  Exelixis'  SEC  Filings.

     8.2  Dispute  Resolution.  Prior  to  the  commencement  of  any
litigation  under  this  Stock  Purchase Agreement, the Parties shall follow the
provisions  set  forth  in  Section  14.2  of  the  Development  Agreement.

     8.3  Governing  Law.  This  Stock  Purchase  Agreement  and  any  dispute
arising from the performance or breach hereof shall be governed by and construed
and  enforced  in  accordance  with  the  laws of the State of Delaware, U.S.A.,
without  reference  to  conflicts  of  laws  principles.

     8.4  Assignment.  This  Stock  Purchase Agreement may be assigned by GSK to
an  Affiliate  without  the  written  consent  of  Exelixis;  but  shall  not be
assignable  by Exelixis, to an Affiliate, or by either Party to any Third Party,
without  the  prior  written consent of the other Party hereto.  Notwithstanding
the  foregoing,  either  Party may assign this Stock Purchase Agreement, without
the  written  consent  of  the other Party, to an Affiliate or to an entity that
acquires  all  or  substantially  all  of  the  business or assets of such Party
(whether  by merger, reorganization, acquisition, sale or otherwise), and agrees
in  writing  to  be  bound  by  the  terms  and conditions of the Stock Purchase
Agreement.  No  assignment  and transfer shall be valid and effective unless and
until  (a)  the  assignee/transferee  shall  agree in writing to be bound by the
provisions of the Stock Purchase Agreement, (b) with respect to an assignment or
transfer  by  Exelixis,  the Loan Documents are assigned/transferred to the same
assignee/transferee concurrently with this Stock Purchase Agreement and (c) with
respect  to  an  assignment  or transfer by Exelixis, the assignee or transferee
shall  have  executed  and  recorded  such  documents  as may be required in the
reasonable  judgment of GSK to perfect GSK's interest in the Collateral (as that
term  in defined in the Loan Agreement) under the Loan Documents.  The terms and
conditions  of the Stock Purchase Agreement shall be binding on and inure to the
benefit  of  the  permitted  successors  and  assigns  of  the  Parties.

     8.5  Performance  Warranty.  Each  Party  hereby  warrants  and  guarantees
the  performance  of  any  and  all  obligations  by  its  Affiliate(s).

     8.6  Notices.  Any  notice  or  request  required  or permitted to be given
under  or  in  connection  with this Stock Purchase Agreement shall be deemed to
have  been  sufficiently given if in writing and personally delivered or sent by
certified  mail  (return  receipt  requested),  facsimile  transmission (receipt
verified),  or  overnight express courier service (signature required), prepaid,
to  the  Party  for  which such notice is intended, at the address set forth for
such  Party  below:

     If  to  Exelixis,
     addressed  to:        Exelixis,  Inc.
                           170  Harbor  Way
                           PO  Box  511
                           South  San  Francisco,  CA  94083
                           Attention:  Chief  Financial  Officer
                           Telephone: [*]
                           Telecopy:  [*]

     with  a  copy  to:    Cooley  Godward  LLP
                           Five  Palo  Alto  Square
                           3000  El  Camino  Real
                           Palo  Alto,  CA  94306
                           Attention:  Robert  L.  Jones,  Esq.
                           Telephone: [*]
                           Telecopy:  [*]

     If  to  GSK,
     addressed  to:        SmithKline  Beecham  Corporation,
                           doing  business  as  GlaxoSmithKline
                           2301  Renaissance  Blvd.  (Bldg.  #510)
                           King  of  Prussia,  Pennsylvania  19406
                           Attention:  Vice  President,  Alliance  and
                           Joint  Venture  Management
                           Telephone: [*]
                           Telecopy:  [*]

     with  a  copy  to:    GlaxoSmithKline
                           Corporate  Legal  Department
                           One  Franklin  Plaza
                           200  N.  16th  Street  /  FP  2355  (DP)
                           Philadelphia,  PA  19103
                           Attention:  Vice  President
                           and  Associate  General  Counsel
                           Telephone: [*]
                           Telecopy:  [*]

or  to  such  other  address  for  such Party as it shall have specified by like
notice  to the other Parties, provided that notices of a change of address shall
be effective only upon receipt thereof.  If delivered personally or by facsimile
transmission,  the date of delivery shall be deemed to be the date on which such
notice  or request was given.  If sent by overnight express courier service, the
date  of  delivery shall be deemed to be the next business day after such notice
or request was deposited with such service.  If sent by certified mail, the date
of  delivery  shall  be deemed to be the third business day after such notice or
request  was  deposited  with  the  U.S.  Postal  Service.

     8.7  Force  Majeure.  No  Party  shall  be  held  liable  or  responsible
to  the  other  Party  nor be deemed to be in default under, or in breach of any
provision  of,  this Stock Purchase Agreement for failure or delay in fulfilling
or  performing any obligation of this Stock Purchase Agreement when such failure
or  delay  is  due  to force majeure, and without the fault or negligence of the
Party  so  failing  or delaying.  For purposes of this Stock Purchase Agreement,
force  majeure  is defined as causes beyond the control of the Party, including,
without  limitation,  acts of God; acts, regulations, or laws of any government;
war; civil commotion; destruction of production facilities or materials by fire,
flood, earthquake, explosion or storm; labor disturbances; epidemic; and failure
of public utilities or common carriers.  In the event of force majeure, Exelixis
or  GSK,  as  the  case may be, shall immediately notify the other Party of such
inability  and  of  the period for which such inability is expected to continue.
The  Party  giving  such  notice  shall  thereupon  be  excused from such of its
obligations  under  this Stock Purchase Agreement as it is thereby disabled from
performing  for  so long as such Party is so disabled, up to a maximum of ninety
(90)  days,  after  which time, the Party not affected by the force majeure, may
terminate  this  Stock  Purchase  Agreement.  To the extent possible, each Party
shall  use  reasonable  efforts  to  minimize the duration of any force majeure.

     8.8  Waiver.  Neither  Party  may  waive  or  release  any of its rights or
interests  in  this  Stock Purchase Agreement except in writing.  The failure of
either  Party  to assert a right hereunder or to insist upon compliance with any
term or condition of this Stock Purchase Agreement shall not constitute a waiver
of that right or excuse a similar subsequent failure to perform any such term or
condition.  No  waiver  by  either  Party of any condition or term in any one or
more  instances  shall  be construed as a continuing waiver of such condition or
term  or  of  another  condition  or  term.

     8.9  Severability.  If  any  provision  hereof  should  be  held  invalid,
illegal  or  unenforceable  in  any jurisdiction, the Parties shall negotiate in
good  faith a valid, legal and enforceable substitute provision that most nearly
reflects  the  original  intent  of  the Parties and all other provisions hereof
shall  remain  in  full  force  and  effect  in  such  jurisdiction and shall be
liberally  construed  in order to carry out the intentions of the Parties hereto
as  nearly  as may be possible.  Such invalidity, illegality or unenforceability
shall  not  affect the validity, legality or enforceability of such provision in
any  other  jurisdiction.

     8.10  Entire  Agreement.  This  Stock Purchase Agreement, together with the
schedules  and  exhibits  hereto, and the accompanying Development Agreement and
Loan  Agreement  set  forth all the covenants, promises, agreements, warranties,
representations,  conditions  and  understandings between the Parties hereto and
supersede  and  terminate  all  prior  agreements  and understanding between the
Parties.  There  are  no  covenants,  promises,  agreements,  warranties,
representations,  conditions  or understandings, either oral or written, between
the  Parties  other  than  as  set  forth  herein  and  therein.  No  subsequent
alteration, amendment, change or addition to this Stock Purchase Agreement shall
be  binding  upon the Parties hereto unless reduced to writing and signed by the
respective  authorized  officers  of  the  Parties.

     8.11  Headings. Headings used herein are for convenience only and shall not
in  any  way  affect  the  construction  of  or  be  taken into consideration in
interpreting  this  Stock  Purchase  Agreement.

     8.12 Use of Name. Any rights or restrictions concerning the use of the name
or  other designation of the Parties or any other trade name, trademark or logos
of  the  Parties  for  any purpose shall be governed by the provision pertaining
thereto  as  set  forth  in  the  Development  Agreement.

     8.13  Further  Actions.  Each  Party shall execute, acknowledge and deliver
such  further  instruments,  and  do all such other acts, as may be necessary or
appropriate in order to carry out the purposes and intent of this Stock Purchase
Agreement.  The  Parties  shall  cooperate  fully  in obtaining any governmental
approvals or consents as may be necessary in order to carry out the purposes and
intent  of  this  Stock  Purchase  Agreement,  including  without limitation any
filings  and  approvals  as  may  be  required  under  the  HSR  Act.

     8.14  Survival  of  Representations and Warranties. All representations and
warranties  contained  herein  shall  survive the execution and delivery of this
Stock  Purchase Agreement, any investigation at any time made by or on behalf of
GSK,  and  the  sale  and  issuance of the Shares and payment therefor until the
earlier  of  (a) the resale of any Shares issued pursuant to this Stock Purchase
Agreement,  or  (b)  the  first  anniversary  of  the  last  Closing.

     8.15  Parties  in  Interest.  All of the terms and provisions of this Stock
Purchase  Agreement  shall  be  binding  upon,  inure  to  the benefit of and be
enforceable  by the Parties hereto and their respective permitted successors and
assigns.

     8.16  Construction  of  Agreement.  The  terms and provisions of this Stock
Purchase Agreement represent the results of negotiations between the Parties and
their  representatives, each of which has been represented by counsel of its own
choosing,  and  neither  of  which has acted under duress or compulsion, whether
legal,  economic  or  otherwise.  Accordingly,  the terms and provisions of this
Stock  Purchase  Agreement shall be interpreted and construed in accordance with
their usual and customary meanings, and each of the Parties hereto hereby waives
the  application  in connection with the interpretation and construction of this
Stock  Purchase  Agreement  of  any  rule of law to the effect that ambiguous or
conflicting terms or provisions contained in this Stock Purchase Agreement shall
be  interpreted  or  construed  against  the  Party  whose attorney prepared the
executed  draft  or  any  earlier  draft  of  this  Stock  Purchase  Agreement.

     8.17  Counterparts.  This  Stock  Purchase  Agreement  may  be  signed  in
counterparts,  each  and  every  one  of  which  shall  be  deemed  an original,
notwithstanding  variations  in format or file designation which may result from
the  electronic  transmission,  storage  and  printing  of  copies of this Stock
Purchase  Agreement  from  separate computers or printers.  Facsimile signatures
shall  be  treated  as  original  signatures.

     8.18  Finder's  Fees.

          8.18.1  Exelixis  (i)  represents and warrants that it has retained no
investment  bankers,  finders  or  brokers  in  connection with the transactions
contemplated  by  this  Stock  Purchase  Agreement  and  (ii)  hereby  agrees to
indemnify  and to hold GSK harmless of and from any costs, expenses or liability
for  any  commission  or  compensation  in  the  nature of a finder's fee to any
investment  banker, finder, broker or other Person or firm (including legal fees
and  other  costs  and  expense  of defending against such liability or asserted
liability)  for  which  it,  or  any  of  its  employees or representatives, are
responsible.

          8.18.2  GSK  (i)  represents  and  warrants  that  it  has retained no
investment  bankers,  finders  or  brokers  in  connection with the transactions
contemplated  by  this  Stock  Purchase  Agreement  and  (ii)  hereby  agrees to
indemnify  and  hold  Exelixis  harmless  of  and  from  any  costs, expenses or
liability  for any commission or compensation in the nature of a finder's fee to
any  investment  banker, finder, broker or other Person or firm (including legal
fees and other costs and expense of defending against such liability or asserted
liability)  for  which  it,  or  any  of  its  employees or representatives, are
responsible.

     8.19  Waiver  of  Jury  Trial.  EACH  PARTY  HERETO  HEREBY  WAIVES, TO THE
FULLEST  EXTENT  PERMITTED BY APPLCABLE LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY
JURY  IN  RESPECT TO ANY LITIGATION DIRECTLY OR INDIRECTLY ARISING OUT OF, UNDER
OR  IN  CONNECTION  WITH  THIS STOCK AGREEMENT.  EACH PARTY HERETO (i) CERTIFIES
THAT  NO  REPRESENTATIVE,  AGENT OR ATTORNEY OF ANY OTHER PARTY HAS REPRESENTED,
EXPRESSLY  OR  OTHERWISE,  THAT  SUCH  OTHER  PARTY  WOULD  NOT, IN THE EVENT OF
LITIGATION, SEEK TO ENFORCE THAT FOREGOING WAIVER, AND (ii) ACKNOWLEDGES THAT IT
AND  THE  OTHER  PARTIES  HERETO  HAVE  BEEN  INDUCED  TO  ENTER INTO THIS STOCK
AGREEMENT  AND  ANY  RELATED INSTRUMENTS, AS APPLICABLE, BY, AMONG OTHER THINGS,
THE  MUTUAL  WAIVERS  AND  CERTIFICATIONS  IN  THIS  SECTION  8.19.

                   [BALANCE OF PAGE INTENTIONALLY LEFT BLANK]


     IN WITNESS WHEREOF, the Parties have executed this Stock Purchase Agreement
by  their  duly  authorized  representatives as of the date first written above.


EXELIXIS,  INC.                          SMITHKLINE  BEECHAM  CORPORATION

By:     /s/  Bob  Myers                  By:     /s/  Donald  F.  Parman
        ---------------------------              --------------------------

Title:  Executive  Vice  President,      Title: Vice President & Secretary
        ---------------------------             ---------------------------
        Pharmaceuticals
        ---------------


[  *  ] = Certain confidential information contained in this document, marked by
brackets, has been omitted and filed separately with the Securities and Exchange
Commission  pursuant  to  Rule  24b-2 of the Securities Exchange Act of 1934, as
amended.



                                  SCHEDULE 4.3

                       SCHEDULE OF OUTSTANDING SECURITIES


Not  applicable  at  the  Initial  Closing.




                                  SCHEDULE 4.6

                      DISCLOSURE OF OUTSTANDING LITIGATION

None.



                                    EXHIBIT A

                          FORM OF OFFICER'S CERTIFICATE


     TO:     SMITHKLINE  BEECHAM  CORPORATION

I  am the duly appointed [Chief Financial Officer] of Exelixis, Inc., a Delaware
corporation ("Exelixis"), and am duly authorized to execute this certificate for
and  on  behalf  of  Exelixis.  For  the  purposes  of  this certificate, "Stock
Purchase  Agreement" means the Stock Purchase and Stock Issuance Agreement dated
as  of  October  28,  2002  by  and  between  SmithKline Beecham Corporation and
Exelixis  and, unless the context otherwise requires, the capitalized terms used
in  this  certificate  shall  have  the  meanings  ascribed to them in the Stock
Purchase  Agreement.

I  do hereby certify in my capacity as [Chief Financial Officer] of Exelixis, on
behalf  of  Exelixis  and  not  in  my  personal  capacity,  as  follows.

1.   The  representations  and  warranties of Exelixis as set forth in the Stock
     Purchase  Agreement are true and correct as of the Closing Date, as if made
     as  of  such  date;  and

2.   No  events  which  have  had  a  Material  Adverse  Effect on Exelixis have
     occurred  during  the  period  used  to calculate the purchase price of the
     shares  of  Common  Stock  of  Exelixis  subject  to  the  Closing.


DATED  at  ______________,  California,  this  __  day  of  _________,  200_.


EXELIXIS,  INC.
by  its  authorized  signatory:


_______________________________________



                                    EXHIBIT B

                       FORM OF COOLEY GODWARD LLP OPINION

1.   Exelixis,  Inc.  (the  "Company") has been duly incorporated and is validly
     existing  as  a corporation in good standing under the laws of the State of
     Delaware.  The Company is qualified as a foreign corporation to do business
     and  is in good standing in the State of California and, to the best of our
     knowledge,  is  not  required  to  qualify  as  a foreign corporation to do
     business  in  any  other  jurisdiction  in  the  United  States.

2.   The  Company  has  the  corporate  power  and authority to own or lease its
     property  and  to  conduct  its  business  as  currently  conducted  and as
     described  in  the  SEC  Filings,  and  to  enter  into  the Stock Purchase
     Agreement,  issue  the  Shares and to carry out and perform its obligations
     under  the  Stock  Purchase  Agreement.

3.   The  Stock  Purchase  Agreement  has  been  duly  authorized,  executed and
     delivered  by, and is a legal, valid and binding agreement of, the Company,
     enforceable  in  accordance  with  its  terms, except as enforcement may be
     limited  by  applicable  bankruptcy,  insolvency  or similar laws affecting
     creditors' rights generally and subject to general principles of equity and
     to  limitations  on  availability  of  equitable relief, including specific
     performance,  and  except  as  rights  to  indemnification in Section 7.1.6
     thereof  may  be  limited  under  applicable  law.

4.   The  Shares  have  been  duly  authorized and, when issued and delivered in
     accordance  with the terms of the Stock Purchase Agreement, will be validly
     issued, fully paid and non-assessable, and the issuance of such Shares will
     not  be  subject  to  any  preemptive or, to our knowledge, similar rights.

5.   With  respect  to  the  issuance of Initial Shares and Option Shares: Based
     upon  the  representations, warranties and agreements of SmithKline Beecham
     Corporation (the "Purchaser") in Article 5 of the Stock Purchase Agreement,
     the  offer and sale of the Shares to the Purchaser under the Stock Purchase
     Agreement  are  exempt from the registration requirements of the Securities
     Act.

     With  respect  to  the issuance of Stock Repayment Shares: The registration
     statement  covering  the Shares was declared effective under the Securities
     Act  at  ______ [a.m./p.m.] on ___________, 20__, and, to our knowledge, no
     stop  order suspending the effectiveness of such registration statement has
     been  issued  and,  to  our  knowledge,  no  proceeding by the SEC for that
     purpose  is  pending.

6.   The  execution and delivery of the Stock Purchase Agreement will not result
     in any violation of, be in conflict with, or constitute a default under (i)
     any  provision  of  the  Company's  Amended  and  Restated  Certificate  of
     Incorporation  or  Amended and Restated Bylaws or (ii) any provision of any
     judgment, decree or order to which the Company is a party or by which it is
     bound  and  of  which  we  have  knowledge.


                                    EXHIBIT C

                             INSTRUMENT OF ADHERENCE

     Reference  is hereby made to that certain Stock Purchase and Stock Issuance
Agreement,  dated  as  of  October  28, 2002, between Exelixis, Inc., a Delaware
corporation  ("Exelixis"), and SmithKline Beecham Corporation ("GSK"), as may be
amended  and  in  effect  from  time  to  time (the "Stock Purchase Agreement").
Capitalized  terms  used  herein  without  definition  shall have the respective
meanings  ascribed  thereto  in  the  Agreement.

     The  undersigned, in order to become the owner or holder of _______________
shares  (the  "Transferred  Shares")  of Common Stock of Exelixis, hereby agrees
that,  from and after the date hereof, the undersigned has become a party to the
Stock  Purchase Agreement in the capacity of a Permitted Transferee with respect
to such Transferred Shares, and is entitled to all of the benefits under, and is
subject  to  all  of the obligations, restrictions and limitations set forth in,
the Stock Purchase Agreement that are applicable to Permitted Transferees.  This
Instrument  of  Adherence shall take effect and shall become a part of the Stock
Purchase  Agreement  immediately  upon  execution.

     Executed  under  seal  as  of  the  date  set forth below under the laws of
________________.


                                         Signature:_____________________
                                                   Name:
                                                   Title:

Accepted:

Exelixis,  Inc.


By:________________________
   Name:
   Title:
   Date: