Document:

<PAGE>

                                                                   EXHIBIT 10.7

                                  SENOMYX, INC.

                           THIRD AMENDED AND RESTATED
                            INVESTOR RIGHTS AGREEMENT

                                 JANUARY 9, 2001

<PAGE>

                                  SENOMYX, INC.

                           THIRD AMENDED AND RESTATED
                            INVESTOR RIGHTS AGREEMENT

         THIS THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT (the
"AGREEMENT") is entered into as of the 9th day of January, 2001, by and among
SENOMYX, INC., a Delaware corporation (the "COMPANY"), the holders of the
Company's Series A Preferred Stock ("SERIES A PREFERRED") acquired pursuant to
the Series A Preferred Stock Purchase Agreement dated October 1, 1999 (the
"SERIES A AGREEMENT") the holders of the Company's Series B Preferred Stock
("SERIES B PREFERRED") acquired pursuant to the Series B Preferred Stock
Purchase Agreement dated August 10, 2000 (the "SERIES B AGREEMENT"), the holder
of the Company's Series C Preferred Stock ("SERIES C PREFERRED") acquired
pursuant to the Series C Preferred Stock Purchase Agreement dated November 9,
2000 (the "SERIES C AGREEMENT") and the purchaser (the "SERIES D INVESTOR") of
the Company's Series D Preferred Stock ("SERIES D PREFERRED") pursuant to the
Series D Preferred Stock Purchase Agreement dated January 9, 2001 (the "SERIES D
AGREEMENT"). The holders of the Series A Preferred, the Series B Preferred, the
Series C Preferred and the Series D Preferred listed on Exhibit A hereto shall
be referred to hereinafter as the "INVESTORS" and each individually as an
"INVESTOR." This Agreement supersedes and replaces the Second Amended and
Restated Investor Rights Agreement dated November 9, 2000 among the Company and
the holders of the Series A Preferred, the Series B Preferred and the Series C
Preferred (the "PRIOR RIGHTS AGREEMENT").

                                    RECITALS

         WHEREAS, the Investors that are holders of the Series A Preferred,
Series B Preferred and/or Series C Preferred have been granted certain rights
under the Prior Rights Agreement;

         WHEREAS, the Company proposes to sell and issue up to eight hundred
sixty-nine thousand three hundred twenty-eight (869,328) shares of its Series D
Preferred to the Series D Investor pursuant to the Series D Agreement; and

         WHEREAS, as a condition of entering into the Series D Agreement, the
Series D Investor has required that the Company extend to it registration
rights, information rights and other rights as set forth below; and

         WHEREAS, the Company and the Investors desire to amend and restate the
rights and obligations of the Company and the Investors under the Prior Rights
Agreement.

         NOW, THEREFORE, in consideration of the mutual promises,
representations, warranties, covenants and conditions set forth in this
Agreement, the Series A Agreement, the Series B Agreement, the Series C
Agreement and the Series D Agreement, the parties mutually agree as follows:

                                       1.

<PAGE>

SECTION 1. GENERAL

         1.1 DEFINITIONS. Capitalized terms used but not otherwise defined
herein shall have the meanings given such terms in the Series D Agreement. As
used in this Agreement the following terms shall have the following respective
meanings:

         "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended.

         "FORM S-3" means such form under the Securities Act as in effect on the
date hereof or any successor registration form under the Securities Act
subsequently adopted by the SEC which permits inclusion or incorporation of
substantial information by reference to other documents filed by the Company
with the SEC.

         "HOLDER" means any person owning of record Registrable Securities that
have not been sold to the public or any assignee of record of such Registrable
Securities in accordance with Section 2.10 hereof.

         "INITIAL OFFERING" means the Company's first firm commitment
underwritten public offering of its Common Stock registered under the Securities
Act.

         "QUALIFYING INITIAL OFFERING" means the Company's first firm commitment
underwritten public offering of its Common Stock registered under the Securities
Act at a per share purchase price of at least $4.2645 (as adjusted for any stock
dividends, combinations, splits, recapitalizations and the like with respect to
such shares), and for total proceeds of at least $15,000,000 (before deduction
of Registration Expenses and Selling Expenses).

         "REGISTER," "REGISTERED," and "REGISTRATION" refer to a registration
effected by preparing and filing a registration statement in compliance with the
Securities Act, and the declaration or ordering of effectiveness of such
registration statement or document.

         "REGISTRABLE SECURITIES" means (a) Common Stock of the Company issued
or issuable upon conversion of the Shares, and (b) any Common Stock of the
Company issued as (or issuable upon the conversion or exercise of any warrant,
right or other security which is issued as) a dividend or other distribution
with respect to, or in exchange for or in replacement of, such above-described
securities. Notwithstanding the foregoing, Registrable Securities shall not
include any securities sold by a person to the public pursuant to a registration
statement or Rule 144 or sold in a private transaction in which the transferor's
rights under Section 2 of this Agreement are not assigned.

         "REGISTRABLE SECURITIES THEN OUTSTANDING" shall be the number of shares
determined by calculating the total number of shares of the Company's Common
Stock that are Registrable Securities and either (a) are then issued and
outstanding or (b) are issuable pursuant to then exercisable or convertible
securities.

         "REGISTRATION EXPENSES" means all expenses incurred by the Company in
complying with Sections 2.2, 2.3 and 2.4 hereof, including, without limitation,
all registration and filing fees, printing expenses, fees and disbursements of
counsel for the Company, reasonable fees and disbursements of a single special
counsel for the Holders, blue sky fees and

                                       2.

<PAGE>

expenses and the expense of any special audits incident to or required by any
such registration (but excluding the compensation of regular employees of the
Company which shall be paid in any event by the Company).

         "SEC" or "COMMISSION" means the Securities and Exchange Commission.

         "SECURITIES ACT" means the Securities Act of 1933, as amended.

         "SELLING EXPENSES" means all underwriting discounts and selling
commissions applicable to the sale.

         "SHARES" means the Company's Series A Preferred issued pursuant to the
Series A Agreement, the Company's Series B Preferred issued pursuant to the
Series B Agreement, the Company's Series C Preferred issued pursuant to the
Series C Agreement, and the Company's Series D Preferred issued pursuant to the
Series D Agreement (including any shares of Series A-1, Series A-2, Series B-1,
Series B-2, or similar series of Preferred Stock issued upon conversion of the
Shares pursuant to the Restated Charter) and held by the Investors listed on
Exhibit A hereto and their permitted assigns.

SECTION 2. REGISTRATION; RESTRICTIONS ON TRANSFER

         2.1 RESTRICTIONS ON TRANSFER.

         (a) Each Holder agrees not to make any disposition of all or any
portion of the Shares or Registrable Securities unless and until:

                  (i) There is then in effect a registration statement under the
         Securities Act covering such proposed disposition and such disposition
         is made in accordance with such registration statement; or

                  (ii) (A) The transferee has agreed in writing to be bound by
         the terms of this Agreement, (B) such Holder shall have notified the
         Company of the proposed disposition and shall have furnished the
         Company with a detailed statement of the circumstances surrounding the
         proposed disposition, and (C) if reasonably requested by the Company,
         such Holder shall have furnished the Company with an opinion of
         counsel, reasonably satisfactory to the Company, that such disposition
         will not require registration of such shares under the Securities Act.
         It is agreed that the Company will not require opinions of counsel for
         transactions made pursuant to Rule 144 except in unusual circumstances.

                  (iii) Notwithstanding the provisions of paragraphs (i) and
         (ii) above, no such registration statement or opinion of counsel shall
         be necessary for a transfer by a Holder which is (A) a partnership to
         its partners or former partners in accordance with partnership
         interests, (B) a limited liability company to its members or former
         members in accordance with their interest in the limited liability
         company, (C) a trust to its grantors or beneficiaries, or (D) to the
         Holder's family member or trust for the benefit of an individual
         Holder; PROVIDED that in each case the transferee will be subject to
         the terms of this Agreement to the same extent as if he were an
         original Holder hereunder.

                                       3.

<PAGE>

         (b) Each certificate representing Shares or Registrable Securities
shall (unless otherwise permitted by the provisions of the Agreement) be stamped
or otherwise imprinted with a legend substantially similar to the following (in
addition to any legend required under applicable state securities laws):

          THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED
          UNDER THE SECURITIES ACT OF 1933 (THE "ACT") AND MAY NOT BE
          OFFERED, SOLD OR OTHERWISE TRANSFERRED, ASSIGNED, PLEDGED
          OR HYPOTHECATED UNLESS AND UNTIL REGISTERED UNDER THE ACT
          OR UNLESS THE COMPANY HAS RECEIVED AN OPINION OF COUNSEL
          SATISFACTORY TO THE COMPANY AND ITS COUNSEL THAT SUCH
          REGISTRATION IS NOT REQUIRED.

         (c) The Company shall be obligated to reissue promptly unlegended
certificates at the request of any holder thereof if the holder shall have
obtained an opinion of counsel (which counsel may be counsel to the Company)
reasonably acceptable to the Company to the effect that the securities proposed
to be disposed of may lawfully be so disposed of without registration,
qualification or legend.

         (d) Any legend endorsed on an instrument pursuant to applicable state
securities laws and the stop-transfer instructions with respect to such
securities shall be removed upon receipt by the Company of an order of the
appropriate blue sky authority authorizing such removal.

         2.2 DEMAND REGISTRATION.

         (a) Subject to the conditions of this Section 2.2, if the Company shall
receive a written request from the Holders of at least a majority of the
Registrable Securities then outstanding (the "INITIATING HOLDERS") that the
Company file a registration statement under the Securities Act covering the
registration of the greater of (i) 20% of the then outstanding Registrable
Securities and (ii) such number of shares of Registrable Securities as to which
the anticipated aggregate offering price to the public would be at least
$5,000,000 (a "QUALIFIED PUBLIC OFFERING"), then the Company shall, within
thirty (30) days of the receipt thereof, give written notice of such request to
all Holders, and subject to the limitations of this Section 2.2, use its best
efforts to effect, as soon as practicable, the registration under the Securities
Act of all Registrable Securities that the Holders request to be registered.

         (b) If the Initiating Holders intend to distribute the Registrable
Securities covered by their request by means of an underwriting, they shall so
advise the Company as a part of their request made pursuant to this Section 2.2
or any request pursuant to Section 2.4 and the Company shall include such
information in the written notice referred to in Section 2.2(a) or Section
2.4(a), as applicable. In such event, the right of any Holder to include its
Registrable Securities in such registration shall be conditioned upon such
Holder's participation in such underwriting and the inclusion of such Holder's
Registrable Securities in the underwriting to the extent provided herein. All
Holders proposing to distribute their securities through such underwriting shall
enter into an underwriting agreement in customary form with the underwriter

                                       4.

<PAGE>

or underwriters selected for such underwriting by a majority in interest of
the Initiating Holders (which underwriter or underwriters shall be reasonably
acceptable to the Company). Notwithstanding any other provision of this
Section 2.2 or Section 2.4, if the underwriter advises the Company that
marketing factors require a limitation of the number of securities to be
underwritten (including Registrable Securities) then the Company shall so
advise all Holders of Registrable Securities which would otherwise be
underwritten pursuant hereto, and the number of shares that may be included
in the underwriting shall be allocated to the Holders of such Registrable
Securities on a PRO RATA basis based on the number of Registrable Securities
held by all such Holders (including the Initiating Holders). Any Registrable
Securities excluded or withdrawn from such underwriting shall be withdrawn
from the registration.

         (c) The Company shall not be required to effect a registration pursuant
to this Section 2.2:

                  (i) prior to the earlier of (A) August 10, 2005 or (B) one (1)
         year following the effective date of the registration statement
         pertaining to the Initial Offering;

                  (ii) after the Company has effected two (2) registrations
         pursuant to this Section 2.2, and such registrations have been declared
         or ordered effective;

                  (iii) during the period starting with the date of filing of,
         and ending on the date one hundred eighty (180) days following the
         effective date of the registration statement pertaining to a public
         offering; PROVIDED that the Company makes reasonable good faith efforts
         to cause such registration statement to become effective;

                  (iv) if within thirty (30) days of receipt of a written
         request from Initiating Holders pursuant to Section 2.2(a), the Company
         gives notice to the Holders of the Company's intention to make a public
         offering within ninety (90) days;

                  (v) if the Company shall furnish to Holders requesting a
         registration statement pursuant to this Section 2.2, a certificate
         signed by the Chairman of the Board stating that in the good faith
         judgment of the Board of Directors of the Company, it would be
         seriously detrimental to the Company and its stockholders for such
         registration statement to be effected at such time, in which event the
         Company shall have the right to defer such filing for a period of not
         more than one hundred eighty (180) days after receipt of the request of
         the Initiating Holders; PROVIDED that such right to delay a request
         shall be exercised by the Company not more than once in any twelve (12)
         month period; or

                  (vi) if the Initiating Holders propose to dispose of shares of
         Registrable Securities that may be immediately registered on Form S-3
         pursuant to a request made pursuant to Section 2.4 below.

         2.3 PIGGYBACK REGISTRATIONS. The Company shall notify all Holders of
Registrable Securities in writing at least thirty (30) days prior to the filing
of any registration statement under the Securities Act for purposes of a public
offering of securities of the Company (including, but not limited to,
registration statements relating to secondary offerings of securities of the
Company, but excluding registration statements relating to employee benefit
plans or with respect to corporate reorganizations or other transactions under
Rule 145 of the Securities Act

                                       5.

<PAGE>

and excluding a Qualifying Initial Offering) and will afford each such Holder
an opportunity to include in such registration statement all or part of such
Registrable Securities held by such Holder. Each Holder desiring to include
in any such registration statement all or any part of the Registrable
Securities held by it shall, within thirty (30) days after the
above-described notice from the Company, so notify the Company in writing.
Such notice shall state the intended method of disposition of the Registrable
Securities by such Holder. If a Holder decides not to include all of its
Registrable Securities in any registration statement thereafter filed by the
Company, such Holder shall nevertheless continue to have the right to include
any Registrable Securities in any subsequent registration statement or
registration statements as may be filed by the Company with respect to
offerings of its securities, all upon the terms and conditions set forth
herein.

                  (a) UNDERWRITING. If the registration statement under which
the Company gives notice under this Section 2.3 is for an underwritten
offering, the Company shall so advise the Holders of Registrable Securities.
In such event, the right of any such Holder to be included in a registration
pursuant to this Section 2.3 shall be conditioned upon such Holder's
participation in such underwriting and the inclusion of such Holder's
Registrable Securities in the underwriting to the extent provided herein. All
Holders proposing to distribute their Registrable Securities through such
underwriting shall enter into an underwriting agreement in customary form
with the underwriter or underwriters selected for such underwriting by the
Company. Notwithstanding any other provision of the Agreement, if the
underwriter determines in good faith that marketing factors require a
limitation of the number of shares to be underwritten, the number of shares
that may be included in the underwriting shall be allocated, first, to the
Company; second, to the Holders on a PRO RATA basis based on the total number
of Registrable Securities held by the Holders; and third, to any shareholder
of the Company (other than a Holder) on a PRO RATA basis. No such reduction
shall reduce the securities being offered by the Company for its own account
to be included in the registration and underwriting. If any Holder
disapproves of the terms of any such underwriting, such Holder may elect to
withdraw therefrom by written notice to the Company and the underwriter,
delivered at least ten (10) business days prior to the effective date of the
registration statement. Any Registrable Securities excluded or withdrawn from
such underwriting shall be excluded and withdrawn from the registration. For
any Holder which is a partnership or corporation, the partners, retired
partners and shareholders of such Holder, or the estates and family members
of any such partners and retired partners and any trusts for the benefit of
any of the foregoing person shall be deemed to be a single "HOLDER", and any
PRO RATA reduction with respect to such "Holder" shall be based upon the
aggregate amount of shares carrying registration rights owned by all entities
and individuals included in such "Holder," as defined in this sentence.

                  (b) RIGHT TO TERMINATE REGISTRATION. The Company shall have
the right to terminate or withdraw any registration initiated by it under
this Section 2.3 prior to the effectiveness of such registration whether or
not any Holder has elected to include securities in such registration. The
Registration Expenses of such withdrawn registration shall be borne by the
Company in accordance with Section 2.5 hereof.

         2.4 FORM S-3 REGISTRATION. In case the Company shall receive from any
Holder or Holders of Registrable Securities a written request or requests that
the Company effect a registration on Form S-3 (or any successor to Form S-3) or
any similar short-form registration

                                       6.

<PAGE>

statement and any related qualification or compliance with respect to all or
a part of the Registrable Securities owned by such Holder or Holders, the
Company will:

                  (a) promptly give written notice of the proposed
registration, and any related qualification or compliance, to all other
Holders of Registrable Securities; and

                  (b) as soon as practicable, effect such registration and
all such qualifications and compliances as may be so requested and as would
permit or facilitate the sale and distribution of all or such portion of such
Holder's or Holders' Registrable Securities as are specified in such request,
together with all or such portion of the Registrable Securities of any other
Holder or Holders joining in such request as are specified in a written
request given within fifteen (15) days after receipt of such written notice
from the Company; PROVIDED, HOWEVER, that the Company shall not be obligated
to effect any such registration, qualification or compliance pursuant to this
Section 2.4:

                           (i) if Form S-3 (or any successor or similar form) is
                  not available for such offering by the Holders; or

                           (ii) if the Holders, together with the holders of any
                  other securities of the Company entitled to inclusion in such
                  registration, propose to sell Registrable Securities and such
                  other securities (if any) at an aggregate price to the public
                  of less than one million dollars ($1,000,000); or

                           (iii) if within thirty (30) days of receipt of a
                  written request from any Holder or Holders pursuant to this
                  Section 2.4, the Company gives notice to such Holder or
                  Holders of the Company's good faith intention to make a public
                  offering within ninety (90) days (other than pursuant to a
                  registration statement relating to employee benefit plan(s) or
                  with respect to a corporate reorganization or other
                  transaction under Rule 145 of the Securities Act); or

                           (iv) if the Company shall furnish to the Holders a
                  certificate signed by the Chairman of the Board of Directors
                  of the Company stating that in the good faith judgment of the
                  Board of Directors of the Company, it would be seriously
                  detrimental to the Company and its shareholders for such Form
                  S-3 registration to be effected at such time, in which event
                  the Company shall have the right to defer the filing of the
                  Form S-3 registration statement for a period of not more than
                  one hundred twenty (120) days after receipt of the request of
                  the Holder or Holders under this Section 2.4; PROVIDED, that
                  such right to delay a request shall be exercised by the
                  Company not more than once in any twelve (12) month period, or

                           (v) if the Company has, within the twelve (12) month
                  period preceding the date of such request, already effected
                  one (1) registration on Form S-3 for the Holders pursuant to
                  this Section 2.4, or

                           (vi) in any particular jurisdiction in which the
                  Company would be required to qualify to do business or to
                  execute a general consent to service of process in effecting
                  such registration, qualification or compliance.

                                       7.

<PAGE>

                  (c) Subject to the foregoing, the Company shall file a Form
S-3 registration statement covering the Registrable Securities and other
securities so requested to be registered as soon as practicable after receipt
of the request or requests of the Holders. Registrations effected pursuant to
this Section 2.4 shall not be counted as demands for registration or
registrations effected pursuant to Sections 2.2 or 2.3, respectively.

         2.5 EXPENSES OF REGISTRATION. Except as specifically provided herein,
all Registration Expenses incurred in connection with any registration,
qualification or compliance pursuant to Section 2.2 or any registration under
Section 2.3 or Section 2.4 herein shall be borne by the Company. All Selling
Expenses incurred in connection with any registrations hereunder, shall be borne
by the holders of the securities so registered PRO RATA on the basis of the
number of shares so registered. The Company shall not, however, be required to
pay for expenses of any registration proceeding begun pursuant to Section 2.2 or
2.4, the request of which has been subsequently withdrawn by the Initiating
Holders unless (a) the withdrawal is based upon material adverse information
concerning the Company of which the Initiating Holders were not aware at the
time of such request, or (b) the Holders of a majority of Registrable Securities
agree to forfeit their right to one requested registration pursuant to Section
2.2 or Section 2.4, as applicable, in which event such right shall be forfeited
by all Holders). If the Holders are required to pay the Registration Expenses,
such expenses shall be borne by the holders of securities (including Registrable
Securities) requesting such registration in proportion to the number of shares
for which registration was requested. If the Company is required to pay the
Registration Expenses of a withdrawn offering pursuant to clause (a) above, then
the Holders shall not forfeit their rights pursuant to Section 2.2 or Section
2.4 to a demand registration.

         2.6 OBLIGATIONS OF THE COMPANY. Whenever required to effect the
registration of any Registrable Securities, the Company shall, as expeditiously
as reasonably possible:

                  (a) Prepare and file with the SEC a registration statement
with respect to such Registrable Securities and use all reasonable efforts to
cause such registration statement to become effective, and, upon the request
of the Holders of a majority of the Registrable Securities registered
thereunder, keep such registration statement effective for up to ninety (90)
days or, if earlier, until the Holder or Holders have completed the
distribution related thereto. The Company shall not be required to file,
cause to become effective or maintain the effectiveness of any registration
statement that contemplates a distribution of securities on a delayed or
continuous basis pursuant to Rule 415 under the Securities Act.

                  (b) Prepare and file with the SEC such amendments and
supplements to such registration statement and the prospectus used in
connection with such registration statement as may be necessary to comply
with the provisions of the Securities Act with respect to the disposition of
all securities covered by such registration statement for the period set
forth in paragraph (a) above.

                  (c) Furnish to the Holders such number of copies of a
prospectus, including a preliminary prospectus, in conformity with the
requirements of the Securities Act, and such other documents as they may
reasonably request in order to facilitate the disposition of Registrable
Securities owned by them.

                                       8.

<PAGE>

                  (d) Use its reasonable best efforts to register and qualify
the securities covered by such registration statement under such other
securities or Blue Sky laws of such jurisdictions as shall be reasonably
requested by the Holders; PROVIDED that the Company shall not be required in
connection therewith or as a condition thereto to qualify to do business or
to file a general consent to service of process in any such states or
jurisdictions.

                  (e) In the event of any underwritten public offering, enter
into and perform its obligations under an underwriting agreement, in usual
and customary form, with the managing underwriter(s) of such offering. Each
Holder participating in such underwriting shall also enter into and perform
its obligations under such an agreement.

                  (f) Notify each Holder of Registrable Securities covered by
such registration statement at any time when a prospectus relating thereto is
required to be delivered under the Securities Act of the happening of any
event as a result of which the prospectus included in such registration
statement, as then in effect, includes an untrue statement of a material fact
or omits to state a material fact required to be stated therein or necessary
to make the statements therein not misleading in the light of the
circumstances then existing.

                  (g) Use its best efforts to furnish, on the date that such
Registrable Securities are delivered to the underwriters for sale, if such
securities are being sold through underwriters, (i) an opinion, dated as of
such date, of the counsel representing the Company for the purposes of such
registration, in form and substance as is customarily given to underwriters
in an underwritten public offering, addressed to the underwriters, if any,
and (ii) a letter dated as of such date, from the independent certified
public accountants of the Company, in form and substance as is customarily
given by independent certified public accountants to underwriters in an
underwritten public offering addressed to the underwriters.

         2.7 TERMINATION OF REGISTRATION RIGHTS. All registration rights granted
under this Section 2 shall terminate and be of no further force and effect seven
(7) years after the date of the Company's Qualifying Initial Offering. In
addition, a Holder's registration rights shall expire if (a) the Company has
completed its Initial Offering and is subject to the provisions of the Exchange
Act, and (b) all Registrable Securities held by and issuable to such Holder (and
its affiliates, partners, former partners, members and former members) may be
sold under Rule 144 (including Rule 144(k)) during any ninety (90) day period.

         2.8 DELAY OF REGISTRATION; FURNISHING INFORMATION.

                  (a) No Holder shall have any right to obtain or seek an
injunction restraining or otherwise delaying any such registration as the
result of any controversy that might arise with respect to the interpretation
or implementation of this Section 2.

                  (b) It shall be a condition precedent to the obligations of
the Company to take any action pursuant to Section 2.2, 2.3 or 2.4 that the
selling Holders shall furnish to the Company such information regarding
themselves, the Registrable Securities held by them and the intended method
of disposition of such securities as shall be required to effect the
registration of their Registrable Securities.

                                       9.
<PAGE>

                  (c) The Company shall have no obligation with respect to any
         registration requested pursuant to Section 2.2 or Section 2.4 if, due
         to the operation of Section 2.2(b), the number of shares or the
         anticipated aggregate offering price of the Registrable Securities to
         be included in the registration does not equal or exceed the number of
         shares or the anticipated aggregate offering price required to
         originally trigger the Company's obligation to initiate such
         registration as specified in Section 2.2 or Section 2.4, whichever is
         applicable.

         2.9 INDEMNIFICATION. In the event any Registrable Securities are
included in a registration statement under Sections 2.2, 2.3 or 2.4:

                  (a) To the extent permitted by law, the Company will indemnify
         and hold harmless each Holder, the partners, officers and directors of
         each Holder, any underwriter (as defined in the Securities Act) for
         such Holder and each person, if any, who controls such Holder or
         underwriter within the meaning of the Securities Act or the Exchange
         Act, against any losses, claims, damages, or liabilities (joint or
         several) to which they may become subject under the Securities Act, the
         Exchange Act or other federal or state law, insofar as such losses,
         claims, damages or liabilities (or actions in respect thereof) arise
         out of or are based upon any of the following statements, omissions or
         violations (collectively a "VIOLATION") by the Company: (i) any untrue
         statement or alleged untrue statement of a material fact contained in
         such registration statement, including any preliminary prospectus or
         final prospectus contained therein or any amendments or supplements
         thereto, (ii) the omission or alleged omission to state therein a
         material fact required to be stated therein, or necessary to make the
         statements therein not misleading, or (iii) any violation or alleged
         violation by the Company of the Securities Act, the Exchange Act, any
         state securities law or any rule or regulation promulgated under the
         Securities Act, the Exchange Act or any state securities law in
         connection with the offering covered by such registration statement;
         and the Company will pay as incurred to each such Holder, partner,
         officer, director, underwriter or controlling person for any legal or
         other expenses reasonably incurred by them in connection with
         investigating or defending any such loss, claim, damage, liability or
         action; PROVIDED HOWEVER, that the indemnity agreement contained in
         this Section 2.9(a) shall not apply to amounts paid in settlement of
         any such loss, claim, damage, liability or action if such settlement is
         effected without the consent of the Company, which consent shall not be
         unreasonably withheld, nor shall the Company be liable in any such case
         for any such loss, claim, damage, liability or action to the extent
         that it arises out of or is based upon a Violation which occurs in
         reliance upon and in conformity with written information furnished
         expressly for use in connection with such registration by such Holder,
         partner, officer, director, underwriter or controlling person of such
         Holder.

                  (b) To the extent permitted by law, each Holder will, if
         Registrable Securities held by such Holder are included in the
         securities as to which such registration qualifications or compliance
         is being effected, indemnify and hold harmless the Company, each of its
         directors, its officers and each person, if any, who controls the
         Company within the meaning of the Securities Act, any underwriter and
         any other Holder selling securities under such registration statement
         or any of such other Holder's partners, directors or officers or any
         person who controls such Holder, against any losses, claims, damages or
         liabilities (joint or several) to which the Company or any such
         director, officer, controlling person, underwriter or other such
         Holder, or partner, director, officer or controlling person of such
         other Holder may become subject under the Securities Act, the Exchange
         Act or other federal or state law, insofar as such losses, claims,

                                       10.

<PAGE>

         damages or liabilities (or actions in respect thereto) arise out of or
         are based upon any Violation, in each case to the extent (and only to
         the extent) that such Violation occurs in reliance upon and in
         conformity with written information furnished by such Holder under an
         instrument duly executed by such Holder and stated to be specifically
         for use in connection with such registration; and each such Holder will
         pay as incurred any legal or other expenses reasonably incurred by the
         Company or any such director, officer, controlling person, underwriter
         or other Holder, or partner, officer, director or controlling person of
         such other Holder in connection with investigating or defending any
         such loss, claim, damage, liability or action if it is judicially
         determined that there was such a Violation; PROVIDED, HOWEVER, that the
         indemnity agreement contained in this Section 2.9(b) shall not apply to
         amounts paid in settlement of any such loss, claim, damage, liability
         or action if such settlement is effected without the consent of the
         Holder, which consent shall not be unreasonably withheld; PROVIDED
         FURTHER, that in no event shall any indemnity under this Section 2.9
         exceed the proceeds from the offering received by such Holder.

                  (c) Promptly after receipt by an indemnified party under this
         Section 2.9 of notice of the commencement of any action (including any
         governmental action), such indemnified party will, if a claim in
         respect thereof is to be made against any indemnifying party under this
         Section 2.9, deliver to the indemnifying party a written notice of the
         commencement thereof and the indemnifying party shall have the right to
         participate in, and, to the extent the indemnifying party so desires,
         jointly with any other indemnifying party similarly noticed, to assume
         the defense thereof with counsel mutually satisfactory to the parties;
         PROVIDED, HOWEVER, that an indemnified party shall have the right to
         retain its own counsel, with the fees and expenses to be paid by the
         indemnifying party, if representation of such indemnified party by the
         counsel retained by the indemnifying party would be inappropriate due
         to actual or potential differing interests between such indemnified
         party and any other party represented by such counsel in such
         proceeding. The failure to deliver written notice to the indemnifying
         party within a reasonable time of the commencement of any such action,
         if materially prejudicial to its ability to defend such action, shall
         relieve such indemnifying party of any liability to the indemnified
         party under this Section 2.9, but the omission so to deliver written
         notice to the indemnifying party will not relieve it of any liability
         that it may have to any indemnified party otherwise than under this
         Section 2.9.

                  (d) If the indemnification provided for in this Section 2.9 is
         held by a court of competent jurisdiction to be unavailable to an
         indemnified party with respect to any losses, claims, damages or
         liabilities referred to herein, the indemnifying party, in lieu of
         indemnifying such indemnified party thereunder, shall to the extent
         permitted by applicable law contribute to the amount paid or payable by
         such indemnified party as a result of such loss, claim, damage or
         liability in such proportion as is appropriate to reflect the relative
         fault of the indemnifying party on the one hand and of the indemnified
         party on the other in connection with the Violation(s) that resulted in
         such loss, claim, damage or liability, as well as any other relevant
         equitable considerations. The relative fault of the indemnifying party
         and of the indemnified party shall be determined by a court of law by
         reference to, among other things, whether the untrue or alleged untrue
         statement of a material fact or the omission to state a material fact
         relates to information supplied by the indemnifying party or by the
         indemnified party and the parties' relative intent, knowledge, access
         to information and opportunity to correct or prevent such statement or
         omission; PROVIDED, that in no event shall any contribution by a Holder
         hereunder exceed the proceeds from the offering received by such
         Holder.

                                       11.

<PAGE>

                  (e) The obligations of the Company and Holders under this
         Section 2.9 shall survive completion of any offering of Registrable
         Securities in a registration statement and the termination of this
         agreement. No indemnifying party, in the defense of any such claim or
         litigation, shall, except with the consent of each indemnified party,
         consent to entry of any judgment or enter into any settlement which
         does not include as an unconditional term thereof the giving by the
         claimant or plaintiff to such indemnified party of a release from all
         liability in respect to such claim or litigation.

         2.10 ASSIGNMENT OF REGISTRATION RIGHTS. The rights to cause the Company
to register Registrable Securities pursuant to this Section 2 may be assigned by
a Holder to a transferee or assignee of Registrable Securities; PROVIDED,
HOWEVER, that (i) the transferor shall, within ten (10) days after such
transfer, furnish to the Company written notice of the name and address of such
transferee or assignee and the securities with respect to which such
registration rights are being assigned, (ii) the transferee or assignee acquires
such Registrable Securities in a private transaction, and (iii) such transferee
shall agree to be subject to all restrictions set forth in this Agreement.

         2.11 AMENDMENT OF REGISTRATION RIGHTS. Any provision of this Section 2
may be amended and the observance thereof may be waived (either generally or in
a particular instance and either retroactively or prospectively), only with the
written consent of the Company and the Holders of at least sixty-seven percent
(67%) of the Registrable Securities then outstanding. Any amendment or waiver
effected in accordance with this Section 2.11 shall be binding upon each Holder
and the Company. By acceptance of any benefits under this Section 2, Holders of
Registrable Securities hereby agree to be bound by the provisions hereunder.

         2.12 LIMITATION ON SUBSEQUENT REGISTRATION RIGHTS. After the date of
this Agreement, the Company shall not, without the prior written consent of the
Holders of sixty-seven percent (67%) of the Registrable Securities then
outstanding, enter into any agreement with any holder or prospective holder of
any securities of the Company that would grant such holder registration rights
senior to those granted to the Holders hereunder.

         2.13 "MARKET STAND-OFF" AGREEMENT; AGREEMENT TO FURNISH INFORMATION.
Each Holder hereby agrees that such Holder shall not sell, transfer, make any
short sale of, grant any option for the purchase of, or enter into any hedging
or similar transaction with the same economic effect as a sale, any Common Stock
(or other securities) of the Company held by such Holder (other than those
included in the registration) for a period specified by the representative of
the underwriters of Common Stock (or other securities) of the Company not to
exceed one hundred eighty (180) days following the effective date of a
registration statement of the Company filed under the Securities Act; PROVIDED
that all officers and directors of the Company enter into similar agreements.

         Each Holder agrees to execute and deliver such other agreements as may
be reasonably requested by the Company or the underwriter which are consistent
with the foregoing or which are necessary to give further effect thereto. In
addition, if requested by the Company or the representative of the underwriters
of Common Stock (or other securities) of the Company, each Holder shall provide,
within ten (10) days of such request, such information as may be required by the
Company or such representative in connection with the completion of any public
offering

                                       12.

<PAGE>

of the Company's securities pursuant to a registration statement filed under
the Securities Act. The obligations described in this Section 2.13 shall not
apply to a registration relating solely to employee benefit plans on Form S-1
or Form S-8 or similar forms that may be promulgated in the future, or a
registration relating solely to a Commission Rule 145 transaction on Form S-4
or similar forms that may be promulgated in the future. The Company may
impose stop-transfer instructions with respect to the shares of Common Stock
(or other securities) subject to the foregoing restriction until the end of
said one hundred eighty (180) day period.

         2.14 RULE 144 REPORTING. With a view to making available to the Holders
the benefits of certain rules and regulations of the SEC which may permit the
sale of the Registrable Securities to the public without registration, the
Company agrees to use its best efforts to:

                  (a) Make and keep public information available, as those terms
         are understood and defined in SEC Rule 144 or any similar or analogous
         rule promulgated under the Securities Act, at all times after the
         effective date of the first registration filed by the Company for an
         offering of its securities to the general public;

                  (b) File with the SEC, in a timely manner, all reports and
         other documents required of the Company under the Exchange Act; and

                  (c) So long as a Holder owns any Registrable Securities,
         furnish to such Holder forthwith upon request: a written statement by
         the Company as to its compliance with the reporting requirements of
         said Rule 144 of the Securities Act, and of the Exchange Act (at any
         time after it has become subject to such reporting requirements); a
         copy of the most recent annual or quarterly report of the Company; and
         such other reports and documents as a Holder may reasonably request in
         availing itself of any rule or regulation of the SEC allowing it to
         sell any such securities without registration.

SECTION 3. COVENANTS OF THE COMPANY

         3.1 BASIC FINANCIAL INFORMATION AND REPORTING.

                  (a) The Company will maintain books and records of account in
         which entries will be made of its business transactions pursuant to a
         system of accounting established and administered in accordance with
         generally accepted accounting principles consistently applied, and will
         set aside on its books all such proper accruals and reserves as shall
         be required under generally accepted accounting principles consistently
         applied.

                  (b) Within one hundred twenty (120) days after the end of each
         fiscal year of the Company, the Company will furnish each Investor who
         is then holding Shares or Registrable Securities a balance sheet of the
         Company, as at the end of such fiscal year, and a statement of income
         and a statement of cash flows of the Company, for such year, all
         prepared in accordance with generally accepted accounting principles
         consistently applied and setting forth in each case in comparative form
         the figures for the previous fiscal year, all in reasonable detail.
         Such financial statements shall be accompanied by a report and opinion
         thereon by independent public accountants of national standing selected
         by the Company's Board of Directors. This subsection (b) shall
         terminate on the earlier of (i) the Qualifying Initial Offering or (ii)
         the date when there are no Registrable Securities outstanding.

                                       13.

<PAGE>

                  (c) The Company will furnish each Investor who is then holding
         Shares or Registrable Securities, within forty-five (45) days after the
         end of the first, second and third quarterly accounting periods in each
         fiscal year of the Company, a balance sheet of the Company as of the
         end of each such quarterly period, and a statement of income and a
         statement of cash flows of the Company for such period and for the
         current fiscal year to date, prepared in accordance with generally
         accepted accounting principles, with the exception that no notes need
         be attached to such statements and year-end audit adjustments may not
         have been made. This subsection (c) shall terminate on the earlier of
         (i) the Qualifying Initial Offering or (ii) the date when there are no
         Registrable Securities outstanding.

                  (d) So long as an Investor (with its affiliates) shall own not
         less than three hundred thousand (300,000) shares of Registrable
         Securities (as adjusted for stock splits and combinations) (a "MAJOR
         INVESTOR"), the Company will furnish each such Major Investor (i) at
         least fifteen (15) days prior to the beginning of each fiscal year an
         annual budget and operating plans for such fiscal year (and as soon as
         available, any subsequent revisions thereto); and (ii) as soon as
         practicable after the end of each month (except for months representing
         the end of an annual or quarterly period (which are governed by
         Sections 3.1(b) and (c) above)), and in any event within twenty (20)
         days thereafter, a balance sheet of the Company as of the end of each
         such month, and a statement of income and a statement of cash flows of
         the Company for such month and for the current fiscal year to date,
         including a comparison to plan figures for such period, prepared in
         accordance with generally accepted accounting principles consistently
         applied, with the exception that no notes need be attached to such
         statements and year-end audit adjustments may not have been made.

                  (e) Notwithstanding the foregoing, the Company shall not be
         required to provide any information that the Company's Board of
         Directors determines to be competitively sensitive information to any
         Holder that is a competitor or potential competitor to the Company, as
         determined in the sole discretion of the Company's Board of Directors.

         3.2 INSPECTION RIGHTS. So long as any Investor continues to hold Shares
or Registrable Securities, such Investor shall have the right to visit and
inspect any of the properties of the Company or any of its subsidiaries, and to
discuss the affairs, finances and accounts of the Company or any of its
subsidiaries with its officers, and to review such information as is reasonably
requested all at such reasonable times and as often as may be reasonably
requested; PROVIDED, HOWEVER, that the Company shall not be obligated under this
Section 3.2 with respect to any Investor then determined in good faith by the
Board of Directors to be a competitor of the Company. This Section 3.2 shall
terminate on the earlier of (i) the Qualifying Initial Offering or (ii) the date
when there are no Registrable Securities outstanding. Notwithstanding the
foregoing, the Company shall not be required to provide any information that the
Company's Board of Directors determines to be competitively sensitive
information to any Holder that is a competitor or potential competitor to the
Company, as determined in the sole discretion of the Company's Board of
Directors.

         3.3 CONFIDENTIALITY OF RECORDS. Each Investor agrees to use, and to use
its best efforts to insure that its authorized representatives use, the same
degree of care as such Investor uses to protect its own confidential information
to keep confidential any information furnished to it which the Company
identifies as being confidential or proprietary (so long as such information

                                       14.

<PAGE>

is not in the public domain), except that such Investor may disclose such
proprietary or confidential information to any partner, subsidiary or parent
of such Investor for the purpose of evaluating its investment in the Company
as long as such partner, subsidiary or parent is advised of the
confidentiality provisions of this Section 3.3. The provisions of this
Section 3.3 shall not apply to information which such Investor can
demonstrate by competent written proof: (a) is now, or hereafter becomes,
through no act or failure to act on the part of such Investor, generally
known or available; (b) is known by such Investor at the time of receiving
such information, as evidenced by its written records; (c) is hereafter
furnished to such Investor by a third party, as a matter of right and without
restriction on disclosure; or (d) is independently developed by the receiving
party, as evidenced by its records, without knowledge of, and without the
aid, application or use of, the disclosing party's confidential information.
In addition, the provisions of this Section 3.3 shall not apply to the extent
that disclosure of confidential information is compelled by law, rule,
regulation or court order.

         3.4 RESERVATION OF COMMON STOCK. The Company will at all times reserve
and keep available, solely for issuance and delivery upon the conversion of the
Preferred Stock, all Common Stock issuable from time to time upon such
conversion.

         3.5 STOCK VESTING. Except as otherwise provided in agreements in effect
on the date hereof, unless otherwise approved by the Board of Directors, all
stock options, other stock equivalents and restricted stock issued after the
date of this Agreement to employees, directors, consultants and other service
providers shall be subject to vesting over four years as follows: (a)
twenty-five percent (25%) of such stock shall vest at the end of the first year
following the earlier of the date of issuance or such person's services
commencement date with the Company, and (b) seventy-five percent (75%) of such
stock shall vest in equal monthly installments over the remaining three (3)
years. With respect to any shares of stock purchased by any such person, the
Company's repurchase option shall provide that upon such person's termination of
employment or service with the Company, with or without cause, the Company or
its assignee (to the extent permissible under applicable securities laws and
other laws) shall have the option to purchase at cost any unvested shares of
stock held by such person.

         3.6 PROPRIETARY INFORMATION AND INVENTIONS AGREEMENT. The Company shall
require all employees to execute and deliver a Proprietary Information and
Inventions Agreement substantially in the form attached to the Series D
Agreement.

         3.7 DIRECTORS' EXPENSES. The Company shall reimburse reasonable costs
incurred by non-employee directors of the Company in attending meetings of the
Company's Board of Directors.

         3.8 QUALIFIED SMALL BUSINESS. For so long as any of the Shares are held
by an Investor (or a transferee in whose hands such Shares are eligible to
qualify as "QUALIFIED SMALL BUSINESS STOCK" as defined in Section 1202(c) of the
Internal Revenue Code of 1986, as amended (the "Code")), the Company will use
its reasonable efforts to comply with the reporting and record keeping
requirements of Section 1202 of the Code, any regulations promulgated thereunder
and any similar state laws and regulations.

                                       15.

<PAGE>

         3.9 OBSERVATION RIGHTS. The Company shall allow one representative
designated by each of Prospect Venture Partners, LP and Rho Management Trust I
to attend all meetings of the Company's Board of Directors in a nonvoting
capacity, and in connection therewith, the Company shall give such
representative copies of all notices, minutes, consents and other materials,
financial or otherwise, which the Company provides to its Board of Directors;
PROVIDED, HOWEVER, that the Company reserves the right to exclude such
representative from access to any material or meeting or portion thereof if the
Company believes upon advice of counsel that such exclusion is reasonably
necessary to preserve the attorney-client privilege, to protect confidential
proprietary information or for other similar reasons.

         3.10 TERMINATION OF COVENANTS. All covenants of the Company contained
in Section 3 of this Agreement shall expire and terminate as to each Investor
upon the earlier of (i) the effective date of the registration statement
pertaining to the Qualifying Initial Offering or (ii) upon (a) a sale, lease or
other disposition of all or substantially all of the assets of the Company or
(b) any consolidation or merger of the Company with or into any other
corporation or other entity or person, or any other corporate reorganization, in
which the stockholders of the Company immediately prior to such consolidation,
merger or reorganization own less than fifty percent (50%) of the Company's
voting power immediately after such consolidation, merger or reorganization, or
any transaction or series of related transactions to which the Company is a
party in which in excess of fifty percent (50%) of the Company's voting power is
transferred (each, a "CHANGE IN CONTROL"); PROVIDED, HOWEVER, that this Section
3.10 shall not apply to a merger effected exclusively for the purpose of
changing the domicile of the Company.

SECTION 4. RIGHTS OF FIRST REFUSAL

         4.1 SUBSEQUENT OFFERINGS. Subject to Section 4.7 below, each Investor
shall have a right of first refusal to purchase its PRO RATA share of all Equity
Securities, as defined below, that the Company may, from time to time, propose
to sell and issue after the date of this Agreement, other than the Equity
Securities excluded by Section 4.6 hereof. Each Investor's PRO RATA share is
equal to the ratio of (a) the number of shares of the Company's Common Stock
(including all shares of Common Stock issued or issuable upon conversion of the
Shares) of which such Investor is deemed to be a holder immediately prior to the
issuance of such Equity Securities to (b) the total number of shares of the
Company's outstanding Common Stock (including all shares of Common Stock issued
or issuable upon conversion of the Shares or upon the exercise of any
outstanding warrants or options) immediately prior to the issuance of the Equity
Securities. The term "EQUITY SECURITIES" shall mean (i) any Common Stock,
Preferred Stock or other security of the Company, (ii) any security convertible,
with or without consideration, into any Common Stock, Preferred Stock or other
security (including any option to purchase such a convertible security), (iii)
any option or other security carrying any warrant or right to subscribe to or
purchase any Common Stock, Preferred Stock or other security or (iv) any such
warrant or right (in each case, as adjusted for any stock dividends,
combinations, splits, recapitalizations and the like).

         4.2 EXERCISE OF RIGHTS. If the Company proposes to issue any Equity
Securities other than Equity Securities referred to in Section 4.6, it shall
give each Investor written notice of its intention, describing the Equity
Securities, the anticipated price and the terms and conditions upon which the
Company proposes to issue the same. Each Investor shall have fifteen (15) days

                                       16.

<PAGE>

from the giving of such notice to agree to purchase its PRO RATA share of the
Equity Securities for the price and upon the terms and conditions specified in
the notice by giving written notice to the Company and stating therein the
quantity of Equity Securities to be purchased. If consented to by holders of at
least fifty percent (50%) of the Registrable Securities then outstanding, no
further such notice shall be required with respect to any changes to the terms
specified in the original notice (except to the extent that any such issuance of
Equity Securities would constitute, or that such changes would cause such
issuance of Equity Securities to become or cease to be, a Dilutive Issuance, as
such term is defined in the Restated Charter). Notwithstanding the foregoing,
the Company shall not be required to offer or sell such Equity Securities to any
Investor who would cause the Company to be in violation of applicable federal
securities laws by virtue of such offer or sale.

         4.3 ISSUANCE OF EQUITY SECURITIES TO OTHER PERSONS. If not all of the
Investors elect to purchase their PRO RATA share of the Equity Securities, then
the Company shall promptly notify in writing the Investors who do so elect and
shall offer such Investors the right to acquire their PRO RATA share of such
unsubscribed shares. The Investors shall have five (5) days after receipt of
such notice to notify the Company of its election to purchase all or a portion
thereof of the unsubscribed shares. If the Investors fail to exercise in full
the rights of first refusal, the Company shall have ninety (90) days thereafter
to sell the Equity Securities in respect of which the Investor's rights were not
exercised, at a price and upon general terms and conditions materially no more
favorable to the purchasers thereof than specified in the Company's notice to
the Investors pursuant to Section 4.2 hereof. If the Company has not sold such
Equity Securities within ninety (90) days of the notice provided pursuant to
Section 4.2, the Company shall not thereafter issue or sell any Equity
Securities, without first offering such securities to the Investors in the
manner provided above.

         4.4 TERMINATION AND WAIVER OF RIGHTS OF FIRST REFUSAL. The rights of
first refusal established by this Section 4 shall not apply to, and shall
terminate upon the earlier of (i) the effective date of the registration
statement pertaining to the Company's Qualifying Initial Offering or (ii) a
Change in Control. The rights of first refusal established by this Section 4 may
be amended, or any provision waived, with the written consent of Investors
holding at least sixty-seven percent (67%) of the Registrable Securities held by
all Investors, or as permitted by Section 5.6.

         4.5 TRANSFER OF RIGHTS OF FIRST REFUSAL. The rights of first refusal of
each Investor under this Section 4 may be transferred to the same parties,
subject to the same restrictions as any transfer of registration rights pursuant
to Section 2.10.

         4.6 EXCLUDED SECURITIES. The rights of first refusal established by
this Section 4 shall have no application to any of the following Equity
Securities:

                  (a) shares of Common Stock and/or options, warrants or other
         Common Stock purchase rights, and the Common Stock issued pursuant to
         such options, warrants or other rights issued or to be issued after the
         Original Issue Date (as defined in the Company's Restated Charter) to
         employees, officers or directors of, or consultants or advisors to, the
         Company or any subsidiary pursuant to stock purchase or stock option
         plans or other arrangements that are approved by the Board of
         Directors;

                                       17.

<PAGE>

                  (b) any Equity Securities issued pursuant to any rights or
         agreements outstanding as of the Original Issue Date or pursuant to the
         exercise of options, warrants or convertible securities outstanding as
         of the Original Issue Date;

                  (c) any Equity Securities issued pursuant to a merger,
         consolidation, acquisition or similar business combination approved by
         the Board of Directors;

                  (d) any Equity Securities issued in connection with any stock
         split, stock dividend, combination or recapitalization by the Company;

                  (e) any Equity Securities issued upon conversion of the
         Preferred Stock of the Company;

                  (f) any Equity Securities issued pursuant to any equipment or
         real estate leasing or loan arrangement, or debt financing from a
         landlord or bank (or similar financial or lending institution);

                  (g) any Equity Securities that are issued by the Company
         pursuant to a registration statement filed under the Securities Act;
         and

                  (h) any Equity Securities issued in connection with strategic
         transactions approved by the Board involving the Company and other
         entities, including (i) joint ventures, manufacturing, marketing or
         distribution arrangements, or (ii) technology license, transfer or
         development arrangements.

         4.7 EXCLUSION OF SERIES C AND SERIES D INVESTOR. Notwithstanding
anything to the contrary herein, neither the Series C Investor, the Series D
Investor nor their transferees shall be entitled to the right of first refusal
or any other right provided by this Section 4.

SECTION 5. MISCELLANEOUS

         5.1 GOVERNING LAW. This Agreement shall be governed by and construed
under the laws of the State of California as applied to agreements among
California residents entered into and to be performed entirely within
California.

         5.2 SURVIVAL. The representations, warranties, covenants and agreements
made herein shall survive any investigation made by any Holder and the closing
of the transactions contemplated hereby. All statements as to factual matters
contained in any certificate or other instrument delivered by or on behalf of
the Company pursuant hereto in connection with the transactions contemplated
hereby shall be deemed to be representations and warranties by the Company
hereunder solely as of the date of such certificate or instrument.

         5.3 SUCCESSORS AND ASSIGNS. Except as otherwise expressly provided
herein, the provisions hereof shall inure to the benefit of, and be binding
upon, the successors, assigns, heirs, executors, and administrators of the
parties hereto and shall inure to the benefit of and be enforceable by each
person who shall be a holder of Registrable Securities from time to time;
PROVIDED, HOWEVER, that prior to the receipt by the Company of adequate written
notice of the transfer of any Registrable Securities specifying the full name
and address of the transferee, the

                                       18.

<PAGE>

Company may deem and treat the person listed as the holder of such shares in
its records as the absolute owner and holder of such shares for all purposes,
including the payment of dividends or any redemption price.

         5.4 ENTIRE AGREEMENT. This Agreement, the Exhibits and Schedules
hereto, the Series D Agreement and the other documents delivered pursuant
thereto constitute the full and entire understanding and agreement between the
parties with regard to the subjects hereof and no party shall be liable or bound
to any other in any manner by any representations, warranties, covenants and
agreements except as specifically set forth herein and therein. The Company and
holders of sixty-seven percent (67%) of the Registrable Securities (as defined
in the Prior Rights Agreement) hereby agree, as evidenced by their signatures
hereto, that all rights granted and covenants made under the Prior Rights
Agreement are hereby waived, released and terminated in their entirety and shall
have no further force or effect whatsoever, including the right of first refusal
set forth in Section 4 of the Prior Rights Agreement, and such holders hereby
further agree and acknowledge that the right of first refusal set forth in
Section 4 of the Prior Rights Agreement did not apply to and is hereby waived
with respect to the Series B Preferred and the Series B Preferred issued
pursuant to the Purchase Agreement. The rights and covenants provided herein set
forth the sole and entire agreement between the parties hereto with respect to
the subject matter hereof.

         5.5 SEVERABILITY. In the event one or more of the provisions of this
Agreement should, for any reason, be held to be invalid, illegal or
unenforceable in any respect, such invalidity, illegality, or unenforceability
shall not affect any other provisions of this Agreement, and this Agreement
shall be construed as if such invalid, illegal or unenforceable provision had
never been contained herein.

         5.6 AMENDMENT AND WAIVER.

                  (a) Except as otherwise expressly provided herein, this
         Agreement may be amended or modified only upon the written consent of
         the Company and the holders of at least sixty-seven percent (67%) of
         the Registrable Securities.

                  (b) Except as otherwise expressly provided herein, the
         obligations of the Company and the rights of the Holders under this
         Agreement may be waived only with the written consent of the holders of
         at least sixty-seven percent (67%) of the Registrable Securities.

         Notwithstanding the foregoing, this Agreement may be amended with only
the written consent of the Company to include additional purchasers of Shares as
"Holders" and parties hereto.

         5.7 DELAYS OR OMISSIONS. It is agreed that no delay or omission to
exercise any right, power, or remedy accruing to any Holder, upon any breach,
default or noncompliance of the Company under this Agreement shall impair any
such right, power, or remedy, nor shall it be construed to be a waiver of any
such breach, default or noncompliance, or any acquiescence therein, or of any
similar breach, default or noncompliance thereafter occurring. It is further
agreed that any waiver, permit, consent, or approval of any kind or character on
any Holder's part of any breach, default or noncompliance under the Agreement or
any waiver on such

                                       19.

<PAGE>

Holder's part of any provisions or conditions of this Agreement must be in
writing and shall be effective only to the extent specifically set forth in
such writing. All remedies, either under this Agreement, by law, or otherwise
afforded to Holders, shall be cumulative and not alternative.

         5.8 NOTICES. All notices required or permitted hereunder shall be in
writing and shall be deemed effectively given: (a) upon personal delivery to the
party to be notified, (b) when sent by confirmed telex or facsimile if sent
during normal business hours of the recipient; if not, then on the next business
day, (c) five (5) days after having been sent by registered or certified mail,
return receipt requested, postage prepaid, or (d) one (1) day after deposit with
a nationally recognized overnight courier, specifying next day delivery, with
written verification of receipt. All communications shall be sent to the party
to be notified at the address as set forth on the signature pages hereof or
Exhibit A hereto or at such other address as such party may designate by ten
(10) days advance written notice to the other parties hereto.

         5.9 ATTORNEYS' FEES. In the event that any suit or action is instituted
to enforce any provision in this Agreement, the prevailing party in such dispute
shall be entitled to recover from the losing party all fees, costs and expenses
of enforcing any right of such prevailing party under or with respect to this
Agreement, including, without limitation, such reasonable fees and expenses of
attorneys and accountants, which shall include, without limitation, all fees,
costs and expenses of appeals.

         5.10 TITLES AND SUBTITLES. The titles of the sections and subsections
of this Agreement are for convenience of reference only and are not to be
considered in construing this Agreement.

         5.11 COUNTERPARTS. This Agreement may be executed in any number of
counterparts (which may be delivered by facsimile), each of which shall be an
original, but all of which together shall constitute one instrument.

                                       20.

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this THIRD AMENDED
AND RESTATED INVESTOR RIGHTS AGREEMENT as of the date set forth in the first
paragraph hereof.

COMPANY:                                       INVESTOR:

SENOMYX, INC.                                  THE NORTH AMERICAN NUTRITION
                                               & AGRIBUSINESS FUND, L.P.

By: ____________________________________       By:  NANA Management, L.P.
      Paul A. Grayson, President and           Its: General Partner
      Chief Executive Officer
                                               By:  Bay City Capital LLC
                                               Its: Advisor and Attorney-in-Fact

                                               By: _____________________________

                                               Name: ___________________________

                                               Title: __________________________

              THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                               INVESTORS:

                                               DOMAIN PARTNERS IV, L.P.

                                               By:   One Palmer Square
                                                     Associates IV, L.L.C.
                                               Its:  General Partner

                                               By: _____________________________
                                                    Kathleen K. Schoemaker
                                                    Managing Member

                                               DP IV ASSOCIATES, L.P.

                                               By:   One Palmer Square
                                                     Associates IV, L.L.C.
                                               Its:  General Partner

                                               By: _____________________________
                                                    Kathleen K. Schoemaker
                                                    Managing Member

              THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                               INVESTOR:

                                               PAUL A. GRAYSON

                                               _________________________________

              THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                               INVESTOR:

                                               KEVIN J. KINSELLA, AS TRUSTEE OF
                                               THE KEVIN J. KINSELLA DECLARATION
                                               OF TRUST OF NOVEMBER 2, 1994

                                               By: _____________________________

                                               Name: ___________________________

                                               Title: __________________________

              THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                               INVESTORS:

                                               KINGSBURY CAPITAL PARTNERS
                                               L.P. III

                                               By: _____________________________

                                               Name: ___________________________

                                               Title: __________________________

                                               KINGSBURY CAPITAL PARTNERS
                                               L.P. IV

                                               By: _____________________________

                                               Name: ___________________________

                                               Title: __________________________

              THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                               INVESTORS:

                                               ANDREA STRYER

                                               _________________________________

                                               LUBERT STRYER

                                               _________________________________

              THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                               INVESTOR:

                                               RICHARD L. SCOTT REVOCABLE TRUST

                                               By: _____________________________

                                               Name: ___________________________

                                               Title: __________________________

              THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                               INVESTORS:

                                               OSCAR L. TANG

                                               _________________________________

                                               GRANTOR TRUST FOR TRACY L. TANG

                                               _________________________________
                                               By: Oscar L. Tang, Trustee

                                               GRANTOR TRUST FOR DANA E. TANG

                                               _________________________________
                                               By: Oscar L. Tang, Trustee

                                               GRANTOR TRUST FOR KRISTIN A. TANG

                                               _________________________________
                                               By: Oscar L. Tang, Trustee

                                               MR. AND MRS. KEVIN TANG

                                               _________________________________

                                               _________________________________

              THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                               INVESTOR:

                                               ZUKER FAMILY TRUST

                                               _________________________________
                                               CHARLES S. ZUKER, TRUSTEE

                                               _________________________________
                                               PATRICIA R. ZUKER, TRUSTEE

              THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                               INVESTORS:

                                               ROGER TSIEN

                                               _________________________________

                                               WENDY GLOBE TSIEN

                                               _________________________________

              THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                           INVESTOR:

                                           PROSPECT VENTURE PARTNERS, LP

                                           By:
                                              ----------------------------------
                                                      David Schnell, MD
                                                      Managing Partner

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE
<PAGE>

                                           INVESTOR:

                                           RHO MANAGEMENT TRUST I

                                           By:    Rho Management Company, Inc.,
                                                  as Investment Advisor

                                           By:
                                              ----------------------------------

                                           Name:
                                                --------------------------------

                                           Title:
                                                 -------------------------------

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                           INVESTOR:

                                           STELIOS PAPADOPOULOS

                                           -------------------------------------

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                           INVESTOR:

                                           JORGE E. HIRSCH

                                           -------------------------------------

                                           ARIEL M. HIRSCH

                                           -------------------------------------

                                           RICARDO B. HIRSCH

                                           -------------------------------------

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                           INVESTOR:

                                           DAVID MARINO

                                           -------------------------------------

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE
<PAGE>

                                           INVESTOR:

                                           SPARKS PARTNERS

                                           By:
                                              ---------------------------------

                                           Name:
                                                -------------------------------

                                           Title:
                                                 ------------------------------

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                           INVESTOR:

                                           FOUR PARTNERS

                                           By:
                                              ---------------------------------

                                           Name:
                                                -------------------------------

                                           Title:
                                                 ------------------------------

                                           BAKER TISCH INVESTMENTS LLC

                                           By:
                                              ---------------------------------

                                           Name:
                                                -------------------------------

                                           Title:
                                                 ------------------------------

                                           FBB ASSOCIATES

                                           By:
                                              ---------------------------------

                                           Name:
                                                -------------------------------

                                           Title:
                                                 ------------------------------

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE
<PAGE>

                                          INVESTOR:

                                          ZAFFARONI REVOCABLE TRUST UTD 1-24-86
                                          ALEJANDRO ZAFFARONI - TRUSTEE

                                          -------------------------------------

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                           INVESTOR:

                                           ALEXANDRIA REAL ESTATE EQUITIES

                                           By:
                                              ----------------------------------

                                           Name:
                                                --------------------------------

                                           Title:
                                                 -------------------------------

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE

<PAGE>

                                           INVESTOR:

                                           AURORA BIOSCIENCES CORPORATION

                                           By:
                                              ----------------------------------

                                           Name:
                                                --------------------------------

                                           Title:
                                                 -------------------------------

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE
<PAGE>

                                           INVESTOR:

                                           INCYTE GENOMICS, INC.

                                           By:
                                              ----------------------------------

                                           Name:
                                                --------------------------------

                                           Title:
                                                 -------------------------------

             THIRD AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
                                 SIGNATURE PAGE
<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                             PAGE
                                                                             ----
<S>                                                                          <C>
SECTION 1. GENERAL.............................................................2

  1.1       Definitions........................................................2

SECTION 2. REGISTRATION; RESTRICTIONS ON TRANSFER..............................3

  2.1       Restrictions on Transfer...........................................3

  2.2       Demand Registration................................................4

  2.3       Piggyback Registrations............................................5

  2.4       Form S-3 Registration..............................................6

  2.5       Expenses of Registration...........................................8

  2.6       Obligations of the Company.........................................8

  2.7       Termination of Registration Rights.................................9

  2.8       Delay of Registration; Furnishing Information......................9

  2.9       Indemnification...................................................10

  2.10      Assignment of Registration Rights.................................12

  2.11      Amendment of Registration Rights..................................12

  2.12      Limitation on Subsequent Registration Rights......................12

  2.13      "Market Stand-Off" Agreement; Agreement to Furnish Information....12

  2.14      Rule 144 Reporting................................................13

SECTION 3. COVENANTS OF THE COMPANY...........................................13

  3.1       Basic Financial Information and Reporting.........................13

  3.2       Inspection Rights.................................................14

  3.3       Confidentiality of Records........................................14

  3.4       Reservation of Common Stock.......................................15

  3.5       Stock Vesting.....................................................15

  3.6       Proprietary Information and Inventions Agreement..................15

  3.7       Directors' Expenses...............................................15

  3.8       Qualified Small Business..........................................15

  3.9       Observation Rights................................................16

  3.10      Termination of Covenants..........................................16

SECTION 4. RIGHTS OF FIRST REFUSAL............................................16

  4.1       Subsequent Offerings..............................................16

                                       i.
<PAGE>

                                TABLE OF CONTENTS
                                   (CONTINUED)

<CAPTION>
                                                                             PAGE
                                                                             ----
<S>                                                                          <C>
  4.2       Exercise of Rights................................................16

  4.3       Issuance of Equity Securities to Other Persons....................17

  4.4       Termination and Waiver of Rights of First Refusal.................17

  4.5       Transfer of Rights of First Refusal...............................17

  4.6       Excluded Securities...............................................17

  4.7       Exclusion of Series C and Series D Investor.......................18

SECTION 5. MISCELLANEOUS......................................................18

  5.1       Governing Law.....................................................18

  5.2       Survival..........................................................18

  5.3       Successors and Assigns............................................18

  5.4       Entire Agreement..................................................19

  5.5       Severability......................................................19

  5.6       Amendment and Waiver..............................................19

  5.7       Delays or Omissions...............................................19

  5.8       Notices...........................................................20

  5.9       Attorneys' Fees...................................................20

  5.10      Titles and Subtitles..............................................20

  5.11      Counterparts......................................................20
</TABLE>

                                       ii.
<PAGE>

                                    EXHIBIT A

                              SCHEDULE OF INVESTORS

<TABLE>
<CAPTION>
                                                          SHARES OF    SHARES OF     SHARES OF     SHARES OF
                                                          SERIES A     SERIES B      SERIES C      SERIES D
                                                          PREFERRED    PREFERRED     PREFERRED     PREFERRED
                     NAME & ADDRESS                         STOCK        STOCK         STOCK         STOCK
--------------------------------------------------------  ---------    ---------     ---------     ---------
<S>                                                       <C>          <C>           <C>           <C>
THE NORTH AMERICAN NUTRITION AND                          2,110,446     499,441              0            0
AGRIBUSINESS FUND, L.P.
   Lori Robson, Ph.D.
   750 Battery Street, Suite 600
   San Francisco, CA 94111
   (415) 835-9346
   (415) 837-0503 - Fax
   attn:  Roger Salquist

DOMAIN PARTNERS IV, L.P.                                  1,717,444     126,841              0            0
   Jim Blair
   One Palmer Square
   Princeton, NJ 08542
   (609) 683-5656
   (609) 683-9789 - Fax
   cc:  Lisa Kraeutler

PROSPECT VENTURE PARTNERS, LP                             1,406,964     342,731              0            0
   David Schnell, M.D.
   435 Tasso Street, Suite 200
   Palo Alto, CA  94305
   (650) 327-8800
   (650) 324-8838 - Fax

KINGSBURY CAPITAL PARTNERS L.P. III                       1,055,223      70,065              0
   Tim Wollaeger
   3655 Nobel Drive, Suite 490
   San Diego, CA 92122
   (858) 677-0600
   (858) 677-0800 - Fax

KINGSBURY CAPITAL PARTNERS L.P. IV                                0     165,000              0            0
   Tim Wollaeger
   3655 Nobel Drive, Suite 490
   San Diego, CA 92122
   (858) 677-0600
   (858) 677-0800 - Fax

                                      A-1
<PAGE>

<CAPTION>
                                                          SHARES OF    SHARES OF     SHARES OF     SHARES OF
                                                          SERIES A     SERIES B      SERIES C      SERIES D
                                                          PREFERRED    PREFERRED     PREFERRED     PREFERRED
                     NAME & ADDRESS                         STOCK        STOCK         STOCK         STOCK
--------------------------------------------------------  ---------    ---------     ---------     ---------
<S>                                                       <C>          <C>           <C>           <C>
RHO MANAGEMENT TRUST I                                      703,482     186,021              0            0
   Mark Leschly
   152 West 57th Street, 23rd Floor
   New York, NY 10019
   (212) 751-6677 ext. 414
   (212) 751-3613 - Fax
   cc: Greg Todd, Esq., Legal Counsel
   888 7th Avenue, Suite 4500
   New York, NY 10019
   (212) 246-5151
   (212) 246-5454 - Fax

MR. AND MRS. KEVIN TANG                                     281,392           0              0            0
   11 Riverside Drive, Apt. 12FW
   New York, NY 10023
   (212) 501-9109
   (212) 471-4943 - Fax

KEVIN J. KINSELLA,  AS TRUSTEE OF THE KEVIN J. KINSELLA     220,740           0              0            0
DECLARATION OF TRUST OF NOVEMBER 2, 1994
   1735 Castellana Road
   La Jolla, CA 92037
   (858) 459-6667
   (858) 623-3395 - Fax

RICHARD L. SCOTT REVOCABLE TRUST                            140,696           0              0            0
   c/o Richard L. Scott Investments, LLC
   100 First Stamford Place, Suite 625
   Stamford, CT 06902
   (203) 602-2290
   (203) 602-7758 - Fax

LUBERT STRYER, M.D.                                         133,568           0              0            0
   843 Sonoma Terrace
   Stanford, CA 94305
   (650) 723-5358
   (650) 498-5351- Fax

OSCAR TANG                                                  105,523           0              0            0
   c/o Gwen Winkhaus
   Reich & Tang
   600 Fifth Avenue
   New York, NY 10020
   (212) 830-5303
   (212) 265-9752 - Fax

                                      A-2
<PAGE>

<CAPTION>
                                                          SHARES OF    SHARES OF     SHARES OF     SHARES OF
                                                          SERIES A     SERIES B      SERIES C      SERIES D
                                                          PREFERRED    PREFERRED     PREFERRED     PREFERRED
                     NAME & ADDRESS                         STOCK        STOCK         STOCK         STOCK
--------------------------------------------------------  ---------    ---------     ---------     ---------
<S>                                                       <C>          <C>           <C>           <C>

TRACY L. TANG                                               105,522           0              0            0
   c/o Gwen Winkhaus
   Reich & Tang
   600 Fifth Avenue
   New York, NY 10020
   (212) 830-5303
   (212) 265-9752 - Fax

DANA E. TANG                                                105,522           0              0            0
   c/o Gwen Winkhaus
   Reich & Tang
   600 Fifth Avenue
   New York, NY 10020
   (212) 830-5303
   (212) 265-9752 - Fax

KRISTIN A. TANG                                             105,522           0              0            0
   c/o Gwen Winkhaus
   Reich & Tang
   600 Fifth Avenue
   New York, NY 10020
   (212) 830-5303
   (212) 265-9752 - Fax

PAUL A. GRAYSON                                              96,728           0              0            0
   C/O Senomyx, Inc.
   11099 North Torrey Pines Road
   La Jolla, CA 92037
   (858) 646-8301
   (858) 404-0750 - Fax

STELIOS PAPADOPOULOS                                         70,348           0              0            0
   3 Somerset Drive South
   Great Neck, NY 11020
   (516) 487-5654
   (516) 487-0245 - Fax

CHARLES S. ZUKER AND PATRICIA R. ZUKER,                      70,348      13,797              0            0
TRUSTEES OF THE ZUKER FAMILY TRUST
   UCSD Cellular & Molecular Medicine
   West, Room 355
   9500 Gilman Drive
   La Jolla, CA 92037
   (858) 534-5528
   (858) 534-8510 - Fax

                                      A-3
<PAGE>

<CAPTION>
                                                          SHARES OF    SHARES OF     SHARES OF     SHARES OF
                                                          SERIES A     SERIES B      SERIES C      SERIES D
                                                          PREFERRED    PREFERRED     PREFERRED     PREFERRED
                     NAME & ADDRESS                         STOCK        STOCK         STOCK         STOCK
--------------------------------------------------------  ---------    ---------     ---------     ---------
<S>                                                       <C>          <C>           <C>           <C>
DP IV ASSOCIATES, L.P.                                       41,155       3,039              0            0
   Jim Blair
   One Palmer Square
   Princeton, NJ 08542
   (609) 683-5656
   (609) 683-9789 - Fax
   cc:  Lisa Kraeutler

ANDREA STRYER                                                36,839           0              0            0
   843 Sonoma Terrace
   Stanford, CA 94305
   (650) 858-2858
   (650) 498-5351- Fax

JORGE E. HIRSCH                                              35,174         836              0            0
   4058 Riverton Place
   San Diego, CA 92130
   (858) 755-2663
   (858) 792-1728 - Fax

ARIEL M. HIRSCH                                                   0       3,500              0            0
   4058 Riverton Place
   San Diego, CA 92130
   (858) 755-2663
   (858) 792-1728 - Fax

RICARDO B. HIRSCH                                                 0       3,500              0            0
   4058 Riverton Place
   San Diego, CA 92130
   (858) 755-2663
   (858) 792-1728 - Fax

ROGER TSIEN                                                  35,174       6,899              0            0
   8535 Nottingham Place
   La Jolla, CA 92037
   (858) 534-4891
   (858) 534-5270 - Fax

WENDY GLOBE TSIEN                                            35,174       6,899              0            0
   8535 Nottingham Place
   La Jolla, CA 92037
   (858) 534-4891
   (858) 534-5270 - Fax

DAVID MARINO                                                 17,587       3,917              0            0
   754 La Canada
   La Jolla, CA 92037
   (619) 238-4393
   (619) 238-1025 - Fax

SPARKS PARTNERS                                              17,587       3,917              0            0
   John Brooks, Secretary
   4146 Roland Avenue

                                      A-4
<PAGE>

<CAPTION>
                                                          SHARES OF    SHARES OF     SHARES OF     SHARES OF
                                                          SERIES A     SERIES B      SERIES C      SERIES D
                                                          PREFERRED    PREFERRED     PREFERRED     PREFERRED
                     NAME & ADDRESS                         STOCK        STOCK         STOCK         STOCK
--------------------------------------------------------  ---------    ---------     ---------     ---------
<S>                                                       <C>          <C>           <C>           <C>
   Baltimore, MD 21211
   (410) 235-3217
   (410) 235-4650 - Fax
   cc: Hugh Rienhoff, Jr., M.D.
   (650) 934-9300
   (650) 934-9376 - Fax

ZAFFARONI REVOCABLE TRUST UTD 1-24-86                             0     779,282              0            0
ALEJANDRO ZAFFARONI - TRUSTEE
   Technofyn Associates LLC
   4005 Miranda Avenue, Suite 180
   Palo Alto, CA  94304
   Attn:   Alejandro Zaffaroni /
           Gonzalo M. Silveira
   (650) 496-2258
   (650) 564-7804 - Fax
   cc:  Julian N. Stern, Esq.
   Heller Ehrman White & McAuliffe LLP
   525 University Avenue
   Palo Alto, CA  94301
   650-324-7000
   650-324-0638 - Fax

FOUR PARTNERS                                                     0     155,856              0            0
   Felix and Geoffrey Baker
   667 Madison Ave., 7th Floor
   New York, NY  10021-8087
   (212) 521-2865
   (212) 521-2915 - Fax

BAKER TISCH INVESTMENTS LLC                                       0      51,952              0            0
   Felix and Julian Baker
   667 Madison Ave., 7th Floor
   New York, NY  10021-8087
   (212) 521-2865
   (212) 521-2915 - Fax

FBB ASSOCIATES                                                    0      51,953              0            0
   Felix and Geoffrey Baker
   667 Madison Ave., 7th Floor
   New York, NY  10021-8087
   (212) 521-2865
   (212) 521-2915 - Fax

ALEXANDRIA REAL ESTATE EQUITIES, L.P.                             0     129,880              0            0
   Joel Marcus, CEO
   135 N. Los Robles Avenue
   Suite 250
   Pasadena, CA 91101
   (626) 578-9693
   (626) 578-0896 - Fax

                                      A-5
<PAGE>

<CAPTION>
                                                          SHARES OF    SHARES OF     SHARES OF     SHARES OF
                                                          SERIES A     SERIES B      SERIES C      SERIES D
                                                          PREFERRED    PREFERRED     PREFERRED     PREFERRED
                     NAME & ADDRESS                         STOCK        STOCK         STOCK         STOCK
--------------------------------------------------------  ---------    ---------     ---------     ---------
<S>                                                       <C>          <C>           <C>           <C>
    cc:  Pete Nelson, CFO

AURORA BIOSCIENCES CORPORATION                                    0           0      1,000,000            0
   11010 Torreyana Road
   San Diego, CA 92121
   (858) 404-6600
   (858404-6743 - Fax
   Attn:  General Counsel

INCYTE GENOMICS, INC.                                             0           0              0      869,328
   3160 Porter Drive
   Palo Alto, CA  94304
   (650) 855-0555
   (650) 845-4166 - Fax
Attn:  Chief Executive Officer

TOTAL                                                     8,648,158   2,605,326      1,000,000      869,328
</TABLE>

                                      A-6<PAGE>
                                                                   Exhibit 10.8

                              [Company Letterhead]

February 8, 2001

Paul A. Grayson
6004 Vista De La Mesa
La Jolla, CA 92037

Re:      Amended and Restated Employment Agreement

Dear Paul:

Senomyx, Inc. (the "Company") is pleased to extend your employment with the
Company effective as of the date set forth above on the following terms.

You will serve as President and Chief Executive Officer and will be responsible
for all such duties as are normally associated with such position. You will
report to the Board of Directors (the "Board") and will be subject to the
direction and policies from time to time established by the Board. You will also
serve as a member of the Board.

You will work out of our principal offices located in La Jolla. You will be
expected to travel as reasonably required by your duties. The Company will
reimburse you for your reasonable travel, entertainment, business and other
expenses incurred in the course of your employment in accordance with Company
policy.

You shall receive an annual base salary of three hundred five thousand dollars
($305,000) effective as of November 1, 2000, payable in regular periodic
payments in accordance with Company policy, less standard payroll deductions and
all other required withholdings. You will be entitled to benefits commensurate
with other senior executives in the Company. In addition, the Company will pay
for supplemental life and disability insurance premiums at levels to be mutally
agreed between you and the Board. You will also be eligible for bonuses, as
shall be determined by the Board. In addition, you will be entitled to not less
than 22 days of paid personal leave per year in addition to the designated
holidays consistent with standard Company policy.

As of this date the Board has granted to you pursuant to the Company's 1999
Equity Incentive Plan, as amended (the "Plan"), an incentive stock option to
purchase up to 400,000 shares of the Company's Common Stock. Such option will
become exercisable ("vest") over four (4) years commencing as of November 1,
2000, with 25% of the shares subject to such option vesting as of November 1,
2001 and the remaining such shares vesting ratably on a monthly basis thereafter
over the remaining three years on the first day of each month following November
1, 2001, all pursuant to the Plan and the Company's standard form of stock
option agreement; provided, however, that vesting shall cease upon the
termination of your Continuous Service (as defined in the Plan). To the extent
such option (in conjunction with any other outstanding incentive stock options
you may have) becomes exercisable for more than the statutory limit in any
calendar year, it will be treated as a non-statutory stock option. You will be
eligible to be considered for future grants under the Plan as determined by the
Board; however, it is expected that you will not be considered for any
additional stock or stock option grants under the Plan for at least two years
from the date of this letter agreement ("Agreement").

<PAGE>

As a Company employee, you will be expected to abide by Company rules and
regulations and acknowledge in writing that you have read the Company's Employee
Handbook which will govern the terms and conditions of your employment. The
Company's Employee Handbook may be modified from time to time at the sole
discretion of the Company.

You will be required to continue to comply with the Proprietary Information and
Inventions Agreement (the "Proprietary Information and Inventions Agreement"),
attached hereto as Exhibit A, which you executed on May 20, 1999, which
prohibits unauthorized use or disclosure of the Company's proprietary
information .

During your employment you shall be permitted to serve on the board of directors
and provide consulting services to charitable organizations and up to two
commercial organizations, for which you may receive compensation, provided that
they do not conflict with your obligations to the Company as described herein,
nor substantially diminish the amount of time you spend with the Company. In
addition, you shall be permitted to make investments that are not directly
related to the primary business and affairs of the Company, and that do not
conflict with your obligations to the Company as described herein. Prior to
joining the board of directors of any such commercial organization, you will
notify the members of the board of the Company to request approval of such
activity, such approval not to be unreasonably denied.

Notwithstanding anything herein to the contrary, your employment relationship
with the Company is "at will." This at-will employment relationship cannot be
changed except in writing, approved by the Board and signed by the Company's
Chairman of the Board. Your "at will" relationship means that you may terminate
your employment with the Company at any time and for any reason whatsoever
simply by notifying the Company in writing. Likewise, the Company may terminate
your employment at any time and for any reason whatsoever, with or without Cause
(as defined herein) or advance notice, by notifying you in writing of such
termination, subject to the provisions stated herein.

In the event your employment is terminated during the term of this Agreement
without Cause (defined below) or you resign during the term of this Agreement
with Good Reason (defined below), and upon your delivery to the Company of a
Release and Waiver in the form attached hereto as Exhibit B that is effective
pursuant to its terms, the Company will provide you with the following benefits:

(i)      the Company will pay a lump sum cash payment equal to the amount of
         your then current annual base salary, less applicable deductions and
         withholdings;

(ii)     the vesting applicable to the option referred to above, any shares
         issued upon early exercise of such option which remain subject to
         vesting and any other Company options or shares of Company stock then
         owned by you shall be accelerated such that all such vesting that would
         have occurred had you remained continuously employed with the Company
         for one (1) year following the date of your termination (the "Severance
         Period") shall be deemed to have occurred as of the date of your
         termination;

(iii)    in the event you elect continued health care coverage for you and your
         family under COBRA, the Company will reimburse you for your COBRA
         premiums during the Severance Period at the same level it paid during
         your employment; and

<PAGE>

(iv)     the Company will make a lump sum cash payment to you in the amount of
         seventy-five thousand dollars ($75,000), less standard deductions and
         withholdings, to cover transitional support.

For purposes of this Agreement, Cause shall be defined as follows:

(i)      your conviction of, or the entry of a pleading of guilty or nolo
         contendere by you to, any crime involving moral turpitude or any
         felony;

(ii)     fraud, embezzlement or theft against the Company;

(iii)    a material breach by you of any material provision of your Proprietary
         Information and Inventions Agreement; or

(iv)     your willful and habitual failure to attend to your duties as assigned
         by the Board which breach, misconduct or non-performance is not cured
         by you within thirty (30) days after you receive written notice from
         the Company of such breach, misconduct or non-performance.

For purposes of this Agreement, "Good Reason" shall mean the occurrence of any
of the following events without your consent:

(i)      a substantial dimunition in the nature, status or prestige of your
         responsibilities, title or reporting level as they exist on the date of
         this Agreement;

(ii)     the relocation of the Company's executive offices or principal business
         location to a point more than fifty (50) miles from the current
         location;

(iii)    a reduction by the Company of your base salary as initially set forth
         herein or as the same may be increased from time to time;

(iv)     any action by the Company (including the elimination of benefit plans
         without providing substitutes thereof or the reduction of your benefits
         thereunder) that would substantially diminish the aggregate value of
         your Company benefits as they exist at such time; or

(v)      a failure by the Company to obtain from any successor, before the
         succession takes place, an agreement to assume and perform all of the
         terms and conditions of this Agreement.

This Agreement shall continue in full force and effect for three (3) years
following the date hereof, unless your employment with the Company is terminated
earlier pursuant to the terms stated herein. Upon the expiration of such three
(3) year period, the term of this Agreement shall automatically be extended by
one (1) year on each anniversary of the date of this Agreement, unless either
party has provided written notice of termination of this Agreement prior to such
anniversary or unless your employment with the Company is terminated earlier
pursuant to the terms stated herein. In no event shall termination of this
Agreement affect any of your rights hereunder which have accrued prior to such
termination, including without limitation any benefits payable upon termination
of your employment as provided for above.

This Agreement, including the Exhibits hereto, and the Employee Handbook, form
the complete and exclusive statement of the terms of your employment with the
Company. The employment terms in this

<PAGE>

Agreement supersede any other agreements or promises made to you by anyone,
whether oral or written, except that the Plan, the Founder's Stock Agreement
entered into by you on February 1, 1999 and any stock option agreements entered
into between you and the Company will govern the terms of your equity incentive
compensation from the Company. Without limiting the foregoing, this Agreement
amends and restates the letter agreement entered into between you and the
Company (formerly known as Ambryx Inc.) on May 13, 1999, which shall no longer
have any force or effect.

This Agreement will be binding upon your heirs, executors, administrators and
other legal representatives and will be binding upon and shall inure to the
benefit of the Company, its successors, and its assigns. The term "Company" as
used herein shall include such successors and assigns to the extent applicable.

Please sign and date this Agreement to evidence your agreement to continue your
employment with the Company under the terms described above.

We look forward to your favorable reply and to a productive and enjoyable work
relationship.

Sincerely,

SENOMYX, INC.

/s/ Dr. Lubert Stryer
------------------------------------------
Dr. Lubert Stryer, Chairman of the Board

Accepted By:

/s/ Paul Grayson
------------------------------------------
Paul Grayson

2/8/01
------------------------------------------
Date

Attachments:      Exhibit A - Proprietary Information and Inventions Agreement
                  Exhibit B - Release and Waiver

<PAGE>

                                    EXHIBIT A

                PROPRIETARY INFORMATION AND INVENTIONS AGREEMENT

<PAGE>

                                    EXHIBIT B

                          RELEASE AND WAIVER OF CLAIMS

         In consideration of the payments and other benefits set forth in the
letter agreement dated February 8, 2001, to which this form is attached, I, PAUL
A. GRAYSON, hereby furnish SENOMYX, INC. (the "Company"), with the following
release and waiver ("Release and Waiver").

         I hereby release, and forever discharge the Company, its officers,
directors, agents, employees, stockholders, successors, assigns, affiliates,
parent, subsidiaries, and benefit plans, of and from any and all claims,
liabilities, demands, causes of action, costs, expenses, attorneys' fees,
damages, indemnities and obligations of every kind and nature, in law, equity,
or otherwise, known and unknown, suspected and unsuspected, disclosed and
undisclosed, arising at any time prior to and including my employment
termination date with respect to any claims relating to my employment and the
termination of my employment, including but not limited to, claims pursuant to
any federal, state or local law relating to employment, including, but not
limited to, discrimination claims, claims under the California Fair Employment
and Housing Act, and the Federal Age Discrimination in Employment Act of 1967,
as amended ("ADEA"), or claims for wrongful termination, breach of the covenant
of good faith, contract claims, tort claims, and wage or benefit claims,
including but not limited to, claims for salary, bonuses, commissions, stock,
stock options, vacation pay, fringe benefits, severance pay or any form of
compensation.

         I also acknowledge that I have read and understand Section 1542 of the
California Civil Code which reads as follows: "A general release does not extend
to claims which the creditor does not know or suspect to exist in his favor at
the time of executing the release, which if known by him must have materially
affected his settlement with the debtor." I hereby expressly waive and
relinquish all rights and benefits under that section and any law of any
jurisdiction of similar effect with respect to any claims I may have against the
Company.

         I acknowledge that, among other rights, I am waiving and releasing any
rights I may have under ADEA, that this Release and Waiver is knowing and
voluntary, and that the consideration given for this Release and Waiver is in
addition to anything of value to which I was already entitled as an executive of
the Company. I further acknowledge that I have been advised, as required by the
Older Workers Benefit Protection Act, that: (a) the Release and Waiver granted
herein does not relate to claims which may arise after this Release and Waiver
is executed; (b) I have the right to consult with an attorney prior to executing
this Release and Waiver (although I may choose voluntarily not to do so); and if
I am over 40 years of age upon execution of this Release and Waiver: (c) I have
twenty-one (21) days from the date of termination of my employment with the
Company in which to consider this Release and Waiver (although I may choose
voluntarily to execute this Release and Waiver earlier); (d) I have seven (7)
days following the execution of this Release and Waiver to revoke my consent to
this Release and Waiver; and (e) this Release and Waiver shall not be effective
until the seven (7) day revocation period has expired.

Date:                                    By:
      ------------------                    ------------------------------------
                                                Paul A. Grayson

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00020-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00020-of-00352.parquet"}]]