<PAGE>
                                                                   Exhibit 10.28

[*] CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
    BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
    EXCHANGE COMMISSION PURSUANT TO RULE 406 OF THE SECURITIES EXCHANGE ACT OF
    1933, AS AMENDED.

                          EXCLUSIVE LICENSE AGREEMENT

                                    BETWEEN

                  THE REGENTS OF THE UNIVERSITY OF CALIFORNIA,

                          THE BOARD OF TRUSTEES OF THE
                       LELAND STANFORD JUNIOR UNIVERSITY

                                      AND

                           CYTOKINETICS, INCORPORATED

                                      FOR

                                      [*]

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.


<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
Article No.                                    Title                                                   Page
-----------                                    -----                                                   ----
<S>                <C>                                                                                 <C>
     1.            DEFINITIONS ....................................................................      2
     2.            EXCLUSIVE GRANT OF LICENSE......................................................      5
     3.            GRANT OF SUBLICENSES............................................................      6
     4.            PAYMENT TERMS...................................................................      7
     5.            LICENSE-ISSUE FEE AND EQUITY....................................................      7
     6.            MILESTONE PAYMENTS..............................................................      8
     7.            EARNED ROYALTIES AND MINIMUM ANNUAL ROYALTIES...................................      9
     8.            DUE DILIGENCE...................................................................     10
     9.            PROGRESS AND ROYALTY REPORTS....................................................     11
     10.           BOOKS AND RECORDS...............................................................     12
     11.           LIFE OF THE AGREEMENT...........................................................     12
     12.           TERMINATION BY UCSD.............................................................     13
     13.           TERMINATION BY LICENSEE.........................................................     13
     14.           DISPOSITION OF LICENSED PRODUCTS ON HAND UPON TERMINATION.......................     13
     15.           USE OF NAMES AND TRADEMARKS.....................................................     14
     16.           LIMITED WARRANTY ...............................................................     14
     17.           PATENT PROSECUTION AND MAINTENANCE .............................................     15
     18.           PATENT MARKING .................................................................     16
     19.           PATENT INFRINGEMENT.............................................................     17
     20.           INDEMNIFICATION ................................................................     18
     21.           NOTICES ........................................................................     19
     22.           ASSIGNABILITY...................................................................     20
     23.           NO WAIVER.......................................................................     20
     24.           FAILURE TO PERFORM..............................................................     20
     25.           GOVERNING LAWS..................................................................     20
     26.           [Intentionally Omitted].........................................................     20
     27.           GOVERNMENT APPROVAL OR REGISTRATION.............................................     20
     28.           EXPORT CONTROL LAWS.............................................................     20
     29.           SECRECY.........................................................................     21
     30.           MISCELLANEOUS...................................................................     22
</TABLE>

<PAGE>
                          EXCLUSIVE LICENSE AGREEMENT

         This License Agreement (the "Agreement") is made effective this 21st
day of April, 1998 (the "Effective Date") between THE BOARD OF TRUSTEES OF THE
LELAND STANFORD JUNIOR UNIVERSITY, a California corporation having offices at
900 Welch Road, Suite 350, Palo Alto CA, 94304, ("Stanford") and THE REGENTS OF
THE UNIVERSITY OF CALIFORNIA, a California corporation having its statewide
administrative offices at 300 Lakeside Drive, 22nd Floor, Oakland, California
94612-3550, ("The Regents"), both being represented by the University of
California, San Diego campus having its office at 9500 Gilman Drive, La Jolla,
CA 92093-0910, ("UCSD"), and CYTOKINETICS, INCORPORATED ("Licensee" or
"CYTOKINETICS"), a Delaware corporation having offices at 2800 Sand Hill Road,
Suite 250, Menlo Park, CA 94025. Stanford and The Regents are collectively
referred to herein as "Licensor."

                                     WHEREAS

         1.       Certain inventions, generally characterized as "[*]," as more
specifically described in (a) UCSD Case Nos. SD97-051, SD98-001, SD98-010 and
SD98-011; (b) UCSF Case No. SF 98-027 (Attorney Docket Number 18557B-000500);
and (c) Stanford Case No. S97-052 (collectively the "Invention"), were made in
the course of research at the UCSD, the University of California, San Francisco
("UCSF"), and Stanford and are covered by Licensor Patent Rights as defined
herein;

         2.       The development of the Invention was sponsored in part by The
National Institutes of Health and The National Science Foundation, and as a
consequence, this license is subject to overriding obligations to the Federal
Government under 35 U.S.C. 200-212 and applicable regulations;

         3.       The inventors are employees of The Regents or Stanford and
have assigned their rights to The Regents or Stanford, respectively;

         4.       Licensee has evaluated the Invention under a Secrecy
Agreements with The Regents (UC Control Numbers 98-20-0009, 98-20-0010,
98-20-0019 and 98-20-0081), and has communicated its evaluation to The Regents;

         5.       Licensee and The Regents have executed a Letter of Intent
dated 7 July, 1997, Control Number 98-30-0012;

         6.       Licensee wishes to obtain rights from Licensor for the
commercial development, use, and sale of products from the Invention and
certain additional technologies as described in this Agreement, and Licensor is
willing to grant those rights so that the

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.
<PAGE>

Invention and certain future technologies may be developed to their fullest and
the benefits enjoyed by the general public; and

         7.       Licensee is a "small business firm" as defined in 15 U.S.C.
632;

         8.       The parties recognize and agree that royalties due under this
Agreement will be paid on both pending patent applications and issued patents;

         9.       Stanford and The Regents have entered into Interinstitutional
Agreements, attached as APPENDIX A and APPENDIX B ("Interinstitutional
Agreements"), pursuant to which the University of California, San Diego ("UCSD")
became authorized to administer the Invention. UCSD's office is located at 9500
Gilman Drive, La Jolla, CA 92093-0910. The Interinstitutional Agreement between
Stanford and The Regents set forth in APPENDIX A has been amended by the parties
thereto; the amendment is included in APPENDIX A.

         10.      The development of the Invention was sponsored in part by the
Howard Hughes Medical Institute ("HHMI"). The Regents acquired the right to
license the Invention from HHMI, under the terms of the Interinstitutional
Agreement between HHMI and The Regents, UC Control No. 86-18-0017. The Regents
are required under the terms of the Interinstitutional Agreement, UC Control No.
86-18-0017, to grant HHMI a paid-up, non-exclusive, royalty-free irrevocable
license to use the Invention for its non-commercial purposes, but with no right
on the part of HHMI to sublicense.

         In view of the foregoing, the parties agree:

1.       DEFINITIONS

         1.1      "Affiliate" means any corporation or other business entity in
which Licensee owns or controls, directly or indirectly, at least twenty percent
(20%) of the outstanding stock or other voting rights entitled to elect
directors, or which owns or controls directly or indirectly at least twenty
percent (20%) of the outstanding stock or other voting rights entitled to elect
directors of Licensee; but in any country where the local law does not permit
foreign equity participation of at least twenty percent (20%), then an
"Affiliate" includes any company in which Licensee owns or controls or is owned
or controlled by, directly or indirectly, the maximum percentage of outstanding
stock or voting rights permitted by local law.

         1.2      "Collaborating Partner" means any third party, including
without limitation, a pharmaceutical or biotechnology company, with which
Licensee or an Affiliate has a contractual relationship relating to the
Invention (i.e., a contractual relationship pursuant to which Licensee or the
Affiliate may grant sublicense rights to the third party with respect to all or
any portion of Licensee's license rights under Section 2.1 of this Agreement),
where any one or more of the following applies: (i) the third party grants to
Licensee or the Affiliate any right to develop, make, have made, use, import,
sell, have sold or distribute any technology, intellectual property or products;
(ii) the third party makes or may become

                                      -2-

<PAGE>

obligated to make payments to Licensee or the Affiliate, or Licensee or the
Affiliate makes or may become obligated to make payments to the third party on
account of research, development or distribution activities or expenses; or
(iii) the third party and Licensee or the Affiliate collaborate in connection
with drug discovery, including without limitation, an arrangement in which the
agreement between the third party and Licensee or the Affiliate creates a joint
research committee, joint development committee or similar body that has members
from both the third party and Licensee or the Affiliate, or an arrangement in
which the third party agrees to contribute or use its own products, technology
or intellectual property in conjunction with rights the third party obtains from
Licensee or the Affiliate.

         1.3      "Device" means an instrument, machine or kit (including
screening or reagent kits and biological materials specifically claimed in
Licensor Patent Rights, but excluding all other biological materials, drugs,
compounds, computer hardware, computer software or computer-robot interfaces)
where all of the following apply: (i) the instrument, machine or kit is designed
for use in and is used in the Field of Use; (ii) the instrument, machine or kit
is sold by Licensee, an Affiliate or a Sublicensee to a third party that is not
a Collaborating Partner; (iii) the instrument, machine or kit is a Licensed
Product; and (iv) the sale or transfer of the instrument, machine or kit by
Licensee, the Affiliate or Sublicensee would constitute, but for the license
granted to Licensee under this Agreement, an infringement of any pending or
issued claim within Licensor Patent Rights.

         1.4      "Field of Use" means all uses in humans or animals, including
all therapeutic and diagnostic uses, but excludes agricultural uses such as
herbicides or pesticides.

         1.5      "First Market Introduction" means the first commercial sale or
commercial transfer to any third party after approval of a New Drug Application
("NDA") by the United States Food and Drug Administration ("FDA") of any Device,
Royalty-Bearing Product or Service.

         1.6      "IND" means an Investigational New Drug Application relating
to any drug resulting from the use of a Licensed Product, Licensed Method or
Technology and approved by the U.S. Food and Drug Administration.

         1.7      "Licensed Method" means any method that is covered by Licensor
Patent Rights, or the use of which would constitute, but for the license granted
to Licensee under this Agreement, an infringement of any pending or issued claim
within Licensor Patent Rights.

         1.8      "Licensed Product" means any product that is covered by
Licensor Patent Rights, that is produced by the Licensed Method, or the use of
which would constitute, but for the license granted to Licensee under this
Agreement, an infringement of any pending or issued claim within Licensor Patent
Rights.

         1.9      "Licensor Patent Rights" means Regents' Patent Rights and
Stanford Patent Rights.

                                      -3-

<PAGE>

         1.10     "Net Sales" means the total of the gross prices actually
received by Licensee or an Affiliate on account of the sale or transfer of
Devices, Royalty-Bearing Products or Services by Licensee, an Affiliate or a
Sublicensee, less the sum of the following actual deductions where applicable:
customary cash, trade, or quantity discounts; sales, use, tariff, import/export
duties or other excise taxes imposed on particular sales; transportation charges
and allowances; and credits to customers because of rejections or returns. For
purposes of calculating Net Sales: (i) if Licensee sells or transfers a Device,
Royalty-Bearing Product or Service to an Affiliate and the Affiliate sells or
transfers such Device, Royalty-Bearing Product or Service, then only the sale by
the Affiliate shall be included in Net Sales, less the deductions described
above (and the sale or transfer by Licensee shall not be included in Net Sales);
and (ii) if Licensee or an Affiliate sells or transfers a Device,
Royalty-Bearing Product or Service to a Sublicensee, then only the sale by the
Sublicensee shall be included in Net Sales, less the deductions described above
(and the sale or transfer by Licensee or the Affiliate shall not be included in
Net Sales).

         1.11     "Phase II Trials" means clinical trials conducted by Licensee
on a limited patient population to determine the effectiveness of the applicable
pharmaceutical for specific targeted indications, to determine dosage tolerance
and optimal dosage and to identify possible adverse side effects and safety
risks.

         1.12     "Regents' Patent Rights" means any subject matter claimed in
or covered by any of the following:

                  a.       Case No. SD97-051 - "[*]," Serial [*];

                  b.       Case No. SD98-001 - "[*]," Serial [*];

                  c.       Case No. SD98-010 - "[*]," Serial [*];

                  d.       Case No. SD98-011 - "[*]," Serial [*];

                  e.       Case No. SF98-027 - "[*]," Serial number pending
(filed by UCSF on April 14, 1998; Attorney Docket Number 18557B-000500);

and continuing applications thereof including divisions, substitutions and
continuation-in-part applications supported by the original application or a
division or substitution (but excluding continuation-in-part applications not
supported by the original application or a division or substitution thereof);
any patents issuing on said applications including reissues, reexaminations and
extensions; and any corresponding foreign applications or patents.

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -4-

<PAGE>

         1.13     "Rights" means Licensed Products and Licensor Patent Rights.

         1.14     "Royalty-Bearing Product" means a Licensed Product that
incorporates drug raw material discovered by Licensor and licensed to Licensee
under this Agreement, and excludes, without limitation, Licensed Products
discovered by Licensee, an Affiliate or sublicensee in whole or in part through
the use of a Licensed Method.

         1.15     "Service" means the screening of compounds by Licensee, an
Affiliate, or Sublicensee as a service for a third party where all of the
following apply: (i) the compounds are supplied by a third party, and Licensee,
the Affiliate or Sublicensee provides to the third party the results of the
screening in exchange for payment by the third party to Licensee, the Affiliate
or Sublicensee; (ii) the third party to whom Licensee is providing the service
is not a Collaborating Partner; and (iii) the screening by Licensee, the
Affiliate or Sublicensee would constitute, but for the license granted to
Licensee under this Agreement, an infringement of any pending or issued claim
within Licensor Patent Rights.

         1.16     "Sublicense" means a sublicense granted by Licensee to a
Sublicensee of Licensee's license rights under Section 2.1 of this Agreement.

         1.17     "Sublicensee" means a third party, other than an Affiliate or
a Collaborating Partner, to which Licensee grants sublicense rights with respect
to Licensee's license rights under Section 2.1 of this Agreement to develop,
make, have made, import, sell, have sold and distribute Licensed Products.

         1.18     "Stanford Patent Rights" means any subject matter claimed in
or covered by Stanford Case No. S97-052 - "[*]," Serial [*], and continuing
applications thereof including divisions, substitutions and continuation-in-part
applications supported by the original application or a division or substitution
(but excluding continuation-in-part applications not supported by the original
application or a division or substitution thereof); any patents issuing on said
applications including reissues, reexaminations and extensions; and any
corresponding foreign applications or patents.

         1.19     "Technology" means all existing information of Licensor (as
reasonably determined by Licensor) relating to Rights to the extent applicable
to the Field of Use, including but not limited to (a) Data of a technical nature
relating to Rights, (b) useful pre-clinical, clinical and other data respecting
the safety and efficacy of Licensed Products, and (c) information that is
necessary or useful in connection with research or development activities, or in
connection with the manufacture, use or sale of Licensed Products or obtaining
governmental approvals relating to Licensed Products.

2.       EXCLUSIVE GRANT OF LICENSE

         2.1      Subject to the limitations set forth in this Agreement,
Licensor grants to Licensee a world-wide license under Licensor Patent Rights to
develop, make, have made,

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -5-

<PAGE>

use, import ??, have sold and distribute Licensed Products and products or
services that arise from ?? of or use Licensed Products, Licensed Methods
and Technology; to practice Licensed Methods; and to use Technology.

         2.2      Except as otherwise provided in this Agreement, the license
granted in Section 2.1 with ?? to Licensor Patent Rights is exclusive for the
life of the Agreement. The license granted in Section 2.1 with respect to
Technology is non-exclusive for the life of this Agreement.

         2.3      The license granted in Sections 2.1 and 2.2 is subject to all
the applicable provisions ?? license to the United States Government executed by
UCSD and is subject to the ?? obligations to the U.S. Government under 35
U.S.C. 200-212 and applicable government ?? regulations.

         2.4      The licenses granted in Sections 2.1 and 2.2 are limited to
the Field of Use. Licensee ?? license under this Agreement outside the Field
of Use. Subject to restrictions imposed by ?? on The Regents, Licensee shall
have the first right to negotiate a license from The ?? future improvements
to the Invention in the Field of Use, provided: (i) such improvements arise from
research funded by Licensee or an Affiliate and performed by the very ?? of
the Invention on a campus governed by the Regents; (ii) such improvements are
solely ?? by The Regents; (iii) the licenses granted in Sections 2.1 and 2.2
remain exclusive; ?? (iv) this Agreement has not been terminated. Such "first
right to negotiate" shall ?? the date Licensee is informed by The Regents of
the improvement and shall terminate ?? therefrom.

         2.5      The Regents and Stanford reserve all rights to use the
Invention and Technology ?? educational and research purposes.

3.       ?? SUBLICENSES

         3.1      Licensor also grants to Licensee the right to issue
sublicenses to third parties under Licensor Patent Rights to make, have made,
use, import and sell and have sold Licensed Products, to practice the Licensed
Method and to use Technology, as long as Licensee has ?? exclusive rights
thereto in the Field of Use under this Agreement. To the extent applicable,
Sublicenses must include all of the rights and obligations due to The Regents
(and, if applicable, the United States Government, HHMI and Stanford) and
contained in this Agreement; provided, however, that sublicensees shall not be
obligated to make any payments to Licensor under Sections 4, 5, 6, 7 or 19.5 of
this Agreement (Licensee shall be responsible for complying with any payment
obligations as described in Sections 4, 5, 6, 7 and 19.5).

         3.2      Licensee shall promptly provide Licensor with a copy of each
sublicense issued and summarize and deliver all reports due Licensor from
sublicensees.

                                      -6-

<PAGE>

         3.3      Upon termination of this Agreement for any reason, Licensor,
at its sole discretion, shall determine whether Licensee shall cancel or assign
to Licensor any and all unexpired sublicenses.

4.       PAYMENT TERMS

         4.1      Royalties are payable on Devices, Royalty-Bearing Products and
Services covered by both pending patent applications and issued patents.
Royalties generated will accrue in each country for the duration of Licensor
Patent Rights in that country and are payable to UCSD when Licensee (or, in the
case of sales by Affiliates, when the Affiliate) receives payment for
Royalty-Bearing Products from a third party.

         4.2      Licensee shall pay earned royalties quarterly on or before
February 28, May 31, August 31 and November 30 of each calendar year. Each
payment will be for earned royalties accrued within Licensee's most recently
completed calendar quarter.

         4.3      All payments due The Regents are payable in United States
Dollars. When Devices, Royalty-Bearing Products and Services are sold for
currencies other than United States Dollars, Licensee shall first determine the
earned royalty in the currency of the country in which Royalty-Bearing Products
were sold and then convert the amount into equivalent United States Dollars,
using the exchange rate quoted in the Wall Street Journal on the last business
day of the calendar quarter when payment was received by Licensee (or, in the
case of sales by Affiliates, when payment was received by the Affiliate).

         4.4      If at any time legal restrictions prevent the remittance of
payments due within 180 days to Licensee from any country where a Device,
Royalty-Bearing Product or Service is sold, Licensee shall pay The Regents
payments owed directly from its U.S. source of funds.

         4.5      If any patent or patent claim within Licensor Patent Rights is
held invalid by a court of competent jurisdiction and last resort and from which
no appeal has or can be taken, all obligation to pay royalties based on that
patent or claim or any claim patentably indistinct therefrom will cease as of
the date of final decision. Licensee will not, however, be relieved from paying
any royalties that accrued and were received before the final decision or that
are based on another patent or claim included within Licensor Patent Rights
that is not involved in the final decision.

         4.6      In the event payments, patent cost reimbursements or fees are
not received by The Regents when due, Licensee shall pay to Licensor interest
charges at a rate of [*] percent ([*]%) per annum. Interest is calculated from
the date payment was due until actually received by The Regents.

5.       LICENSE-ISSUE AND PARTNERSHIP FEE

         5.1      Licensee shall pay to Licensor a license-issue fee of: (i)
[*] ($[*]) within [*] days of the execution of this License Agreement; (ii) [*]

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -7-

<PAGE>

Dollars ($[*]) on the [*] of the Effective Date; and (iii) [*] Dollars ($[*]) on
the [*] of the Effective Date. This fee is non-refundable, non-cancelable, and
is not an advance against royalties. All payments due by Licensee to Licensor
hereunder shall be paid to UCSD. Licensee shall have no liability and Licensee's
rights under this Agreement shall not be affected on account of the failure of
UCSD to pay to Stanford or UCSF amounts due to Stanford or UCSF.

         5.2      Within ten (10) days after receipt by Licensee from a
Collaborating Partner, pursuant to an agreement between Licensee and the
Collaborating Partner in which Licensee (i) grants to the Collaborating Partner
rights to sell, distribute or develop Licensed Products, or (ii) agrees to
collaborate with the Collaborating Partner in drug discovery for use in the
Field of Use using Licensed Products or Licensed Methods, of consideration in
the form of cash, stock purchase or equity investment in Licensee, with a
cumulative value equal to or grater than [*] Dollars ($[*]) but less than [*]
Dollars ($[*]), Licensee shall pay UCSD a partnership fee equal to $[*].
Thereafter, on February 28 of each year Licensee shall pay UCSD an annual
license fee equal to $[*] for each such collaboration agreement so long as the
agreement with the Collaborative Partner has not been terminated and the
Collaborative Partner continues to actively market and sell Licensed Products.
With respect to any Collaborating Partner, the $[*] fees described above shall
be increased to [*] U.S. Dollars ($[*]) when the cumulative consideration
described above received from such Collaborating Partner equals or exceeds [*]
U.S. Dollars ($[*]).

6.       MILESTONE PAYMENTS

Licensee shall pay to Licensor milestone payments in the following amounts
within thirty (30) days following the achievement of the specified events:

         6.1      Within ten (10) days after the filing with the FDA of any IND
for a product discovered using Licensed Products by Licensee, an Affiliate or a
Sublicensee, $[*].

         6.2      Within ten (10) days after the completion of Phase II Trials
(which will not be deemed to be complete until a Final Report for Phase II has
been submitted to and approved by the FDA) by Licensee, an Affiliate or a
Sublicensee for the first Royalty-Bearing Product, $[*]. Licensee shall only be
obligated to make one milestone payment under this Section 6.2.

         6.3      Within ten (10) days after approval by the FDA of an NDA for a
product discovered using Licensed Products filed by Licensee, an Affiliate or a
Sublicensee, $[*].

         6.4      Within ten (10) days after approval by the FDA of an NDA for a
product discovered using Licensed Products filed by a Collaborating Partner,
$[*].

All Milestone Payments made to Licensor prior to First Market Introduction of
any Device, Royalty-Bearing Product or Service shall be credited against
royalties owed to Licensor on

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -8-

<PAGE>

account of such Device, Royalty-Bearing Product or Service. Thereafter,
milestone payments shall not be credited against royalties owed by Licensee to
Licensor.

7.       EARNED ROYALTIES AND MINIMUM ANNUAL ROYALTIES

         7.1      a. Devices. Licensee shall pay to Licensor a royalty equal to:
(i) [*] percent ([*]%) of annual worldwide Net Sales by Licensee, an Affiliate
or a Sublicensee of Devices that do not contain computer hardware, computer
software or computer-robot interfaces; and (ii) [*] percent ([*]%) of annual
worldwide Net Sales by Licensee, an Affiliate or a Sublicensee of Devices that
contain computer hardware, computer software or computer-robot interfaces.

                  b. Royalty-Bearing Products. Licensee shall pay to Licensor a
royalty calculated on annual worldwide Net Sales of Royalty-Bearing Products by
Licensee, an Affiliate or a Sublicensee according to the following schedule:

                           1) [*]% on annual Net Sales of less than $[*];

                           2) [*]% on annual Net Sales greater than $[*], but
less than $[*];

                           3) [*]% on annual Net Sales greater than $[*], but
less than $[*];

                           4) [*]% on annual Net Sales greater than $[*], but
less than $[*];

                           5) [*]% on annual Net Sales greater than $[*].

The royalty schedule described above shall be calculated based upon Net Sales of
Royalty-Bearing Products generated during each calendar year, so that aggregate
Net Sales are separately computed for each calendar year.

                  c. Services. Licensee shall pay to Licensor a royalty equal
to [*] percent ([*]%) of annual worldwide Net Sales of Services by Licensee, an
Affiliate or a Sublicensee.

Except for Devices, Royalty-Bearing Products and Services, no royalties shall be
payable with respect to the sale of Licensed Products, including without
limitation Licensed Products based on drug raw materials discovered in whole or
in part through the use of Licensed Methods such as screens, assays and
molecular targets such as molecular motors and their regulatory elements.

         7.2      Licensee shall have the right to grant sublicenses under this
Agreement for all purposes and indications within the Field of Use. Licensee
shall pay The Regents "Licensor's Share" (defined below) of any "Qualified
Sublicense Payments" (defined below). "Qualified

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -9-

<PAGE>
Sublicense Payments" shall mean up-front payments, milestone payments and the
premium portion over the then-fair market value of any purchase by the
Sublicensee of equity of Licensee, made by a Sublicensee to Licensee during the
term of this Agreement and the term of the applicable Sublicense, to the extent
made on account of the sublicense by Licensee of Licensor Patent Rights, but
shall not include: (i) payments made for the purchase of equity of Licensee to
the extent that the purchase is made at the then-fair market value of the
equity, as determined in good faith by the Board of Directors of Licensee; (ii)
royalties; and (iii) payments made for the purchase of products or services. If
the only license rights granted by Licensee to the Sublicensee consist of
Licensor Patent Rights and/or Licensed Methods (and no other rights, technology
or intellectual property), then "Licensor's Share" shall be [*] percent ([*]%)
of the Qualified Sublicense Payment. If the license rights granted by Licensee
to the Sublicensee include rights, technology or intellectual property in
addition to Licensor Patent Rights and/or Licensed Methods, then "Licensor's
Share" shall be [*] percent ([*]%) of the Qualified Sublicense Payment. Any
Qualified Sublicense Payments made by Sublicensee in a form other than cash
shall be valued at the then-fair market value of such Qualified Sublicense
Payments. If the parties cannot agree on the fair market value of such non-cash
Qualified Sublicense Payments, the parties agree to meet and negotiate in good
faith such fair market value.

         7.3      Licensee shall pay to Licensor a minimum annual royalty of [*]
Dollars ($[*]) for the life of Licensor Patent Rights, beginning with the year
of the First Market Introduction of any Device, Royalty-Bearing Product or
Service, but no later than February 28 of the first full calendar year beginning
after the [*] year anniversary of the Effective Date. For the first year of
commercial sales, if earlier than the [*] year anniversary of the Effective
Date, Licensee's obligation to pay the minimum annual royalty will be pro-rated
for the number of months remaining in that calendar year when commercial sales
commence and will be due the following February 28, to allow for crediting of
the prorated year's earned royalties. For subsequent years, the minimum annual
royalty will be paid to Licensor by February 28 of the year immediately
following the applicable year, and will be credited against the earned royalty
due for the calendar year in which the minimum payment was made.

8.       DUE DILIGENCE

         8.1      Licensee, on execution of this Agreement, shall itself or
through one or more third parties diligently proceed with the development,
manufacture and sale of Licensed Products and shall itself or through one or
more third parties earnestly and diligently endeavor to market the same within a
reasonable time after execution of this Agreement and in quantities sufficient
to meet market demands. Licensee shall develop one or more [*] incorporating
some portion of the Invention within [*] ([*]) months after the Effective Date.
Within [*] ([*]) months after the Effective Date, some combination of Licensee
and/or one or more sublicensees or partners of Licensee shall have initiated at
least [*] ([*]) [*] which [*] shall address at least [*] ([*]) of the following
[*]: [*] that Licensee informs Licensor are suitable [*]

* Certain information on this page has been omitted and filed Separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

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[*]. Licensor expects that the first sale of Licensed Products shall occur
within [*] ([*]) years of the execution date of this Agreement, unless the first
sale of Licensed Products is delayed by the process of regulatory approval by
federal, state or foreign national agencies or by the occurrence of other events
beyond the reasonable control of Licensee.

         8.2      Licensee shall itself or through one or more third parties
endeavor to obtain all necessary governmental approvals for any manufacture, use
or sale of Licensed Products, or shall certify to UCSD in writing that none are
needed.

         8.3      If Licensee (or an Assignee or sublicensee) fails to either:
(1) submit [*] to the [*] within [*] ([*]) years from the Effective Date of this
Agreement; or (2) begin to [*] the [*] within [*] ([*]) months after receiving
[*] of the [*] for such [*]; then UCSD has the right and option to either
terminate this Agreement or reduce Licensee's exclusive license to a
nonexclusive license. This right, if exercised by UCSD, supersedes the rights
granted in Article 2 (GRANT), and shall be exercised, if at all, by written
notice delivered to Licensee within thirty (30) days after the applicable date
described above.

         8.4      In addition to the obligations set forth above, Licensee and
its partners, Affiliates and sublicensees shall collectively spend: (i) [*] $[*]
for the [*] during the [*] ([*]) [*] of this Agreement, and (ii) beginning with
the [*] and continuing through and including the [*], [*] $[*] for any [*] ([*])
[*].

9.       PROGRESS AND ROYALTY REPORTS

         9.1      Beginning February 28, 1998 and semi-annually thereafter,
Licensee shall submit to UCSD a progress report covering Licensee's (and any
Affiliate's) activities related to the development and testing of all Devices,
Royalty-Bearing Products or Services arising from the use of a Licensed Product,
a Licensed Method or the Technology and the obtaining of the governmental
approvals necessary for marketing. Progress reports are required for each
Device, Royalty-Bearing Product or Service until the first commercial sale of
that Device, Royalty-Bearing Product or Service occurs in the United States.

         9.2      Progress reports submitted under Paragraph 9.1 should include,
but are not limited to, the following topics related to the Device,
Royalty-Bearing Product or Service that arise from the use of a Licensed
Product, a Licensed Method or the Technology:

         -        summary of work completed

* Certain information on this page has been omitted and filed Separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -11-

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         -        key scientific discoveries

         -        summary of work in progress

         -        current schedule of anticipated events or milestones

         -        market plans for introduction of Devices, Royalty-Bearing
                  Products or Services arising from the use of a Licensed
                  Product, a Licensed Method or the Technology, and

         -        a summary of resources (dollar value) spent in the reporting
                  period.

         9.3      Licensee has a responsibility to inform UCSD of any change in
its status (or the status of any Affiliate that performs any activities in
connection with this Agreement) as a small business entity (as defined by the
United States Patent and Trademark Office).

         9.4      Licensee shall report to UCSD in its immediately subsequent
progress and royalty report the date of first commercial sale of a Device,
Royalty-Bearing Product or Service in each country.

         9.5      After the first commercial sale of a Royalty-Bearing Product
anywhere in the world, Licensee shall make quarterly royalty reports to UCSD on
or before each February 28, May 31, August 31 and November 30 of each year. Each
royalty report will cover Licensee' most recently completed calendar quarter and
will show (a) the gross sales and Net Sales of Devices, Royalty-Bearing Products
and Services sold during the most recently completed calendar quarter; (b) the
number of each type of Device, Royalty-Bearing Product or Service sold; (c) the
royalties, in U.S. dollars, payable with respect to sales of Devices, Royalty-
Bearing Products or Services; (d) the method used to calculate the royalty; and
(e) the exchange rates used.

         9.6      If no sales of Devices, Royalty-Bearing Products or Services
have been made during any reporting period, a statement to this effect is
required.

10.      BOOKS AND RECORDS

         10.1     Licensee shall keep accurate books and records showing all
Devices, Royalty- Bearing Products and Services manufactured, used, and/or sold
under the terms of this Agreement. Books and records must be preserved for at
least five (5) years from the date of the royalty payment to which they pertain.

         10.2     Licensee' books and records relating to Net Sales must be open
to inspection by representatives or agents of Licensor at reasonable times. UCSD
shall bear the fees and expenses of examination but if an error in royalties of
more than [*] percent ([*]%) of the total royalties due for any year is
discovered in any examination then Licensee shall bear the reasonable fees and
expenses of that examination. Licensor agrees to keep confidential any
information discovered pursuant this Section 10.2 or Sections 9.1 or 9.2.

11.      LIFE OF THE AGREEMENT

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  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -12-

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         11.1     Unless otherwise terminated by operation of law or by acts of
the parties in accordance with the terms of this Agreement, this Agreement will
be in force from the Effective Date until: (1) if a patent that is included
within Licensor Patent Rights is issued, the expiration of the last-to-expire
patent licensed under this Agreement; (2) if no patent that is included within
Licensor Patent Rights is issued, [*] ([*]) years from the date of this
Agreement, unless all patent applications licensed under this Agreement have
been abandoned as of the [*] anniversary of this Agreement (and Licensor has
complied with its obligations in Article 17), in which case this Agreement shall
terminate on the [*] anniversary of this Agreement.

         11.2     Any termination of this Agreement will not affect the rights
and obligations set forth in the following Articles:

                  Article 10   Books and Records

                  Article 14   Disposition of Licensed Products on Hand on
                               Termination

                  Article 15   Use of Names and Trademarks

                  Article 20   Indemnification

                  Article 24   Failure to Perform

                  Article 29   Secrecy

12.      TERMINATION BY UCSD

         If Licensee fails to perform or violates any material term of this
Agreement, then UCSD may give written notice of default ("Notice of Default") to
Licensee. If Licensee fails to repair the default within sixty (60) days of the
effective date of Notice of Default (or, with respect to a default that is not
reasonably curable within sixty (60) days, such additional reasonable period of
time as may be required under the circumstances to cure the default, which
additional period of time in no event shall exceed one hundred eighty (180)
days), UCSD may terminate this Agreement and its licenses by a second written
notice ("Notice of Termination"). If a Notice of Termination is sent to
Licensee, this Agreement will automatically terminate on the effective date of
that notice. Termination will not relieve Licensee of its obligation to pay any
fees owing at the time of termination and will not impair any accrued right of
UCSD. These notices are subject to Article 19 (Notices).

13.      TERMINATION BY LICENSEE

         13.1     Licensee has the right at any time to terminate this Agreement
in whole or as to any portion of Licensor Patent Rights by giving notice in
writing to UCSD. Notice of termination will be subject to Article 19 (Notices)
and termination of this Agreement will be effective ninety (90) days from the
effective date of notice.

         13.2     Any termination under the above paragraph does not relieve
Licensee of any obligation or liability accrued under this Agreement prior to
termination or rescind any payment made to UCSD or anything done by Licensee
prior to the time termination becomes

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -13-

<PAGE>

effective. Termination does not affect in any manner any rights of UCSD arising
under this Agreement prior to termination.

14.      DISPOSITION OF LICENSED PRODUCTS ON HAND UPON TERMINATION

         Upon termination of this Agreement Licensee is entitled to dispose of
all previously made or partially made Licensed Products, but no more, within a
period of [*] ([*]) days provided that the sale of those Licensed Products is
subject to the terms of this Agreement, including but not limited to the
rendering of reports and payment of royalties required under this Agreement.

15.      USE OF NAMES AND TRADEMARKS

         Nothing contained in this Agreement confers any right to use in
advertising, publicity, or other promotional activities any name, trade name,
trademark, or other designation of either party hereto (including contraction,
abbreviation or simulation of any of the foregoing). Unless required by law, the
use by Licensee of the names Stanford University, HHMI, UCSD, UCSF or any other
campus of The Regents is prohibited.

16.      LIMITED WARRANTY

         16.1     The persons executing this Agreement on behalf of the
constituent members of Licensor warrant that they are duly authorized to do so.
Each constituent member of Licensor warrants that this Agreement constitutes the
binding obligation of such constituent member and is enforceable in accordance
with its terms. UCSD has separately provided to Licensee the Interinstitutional
Agreements. The Interinstitutional Agreements shall not be terminated, and may
not be amended in a manner that adversely affect Licensee's rights hereunder.

         16.2     This license and the associated Invention are provided WITHOUT
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR ANY OTHER
WARRANTY, EXPRESS OR IMPLIED. LICENSOR MAKES NO REPRESENTATION OR WARRANTY THAT
THE LICENSED PRODUCTS OR LICENSED METHODS WILL NOT INFRINGE ANY PATENT OR OTHER
PROPRIETARY RIGHT.

         16.3     IN NO EVENT MAY LICENSOR BE LIABLE FOR ANY INCIDENTAL, SPECIAL
OR CONSEQUENTIAL DAMAGES RESULTING FROM EXERCISE OF THIS LICENSE OR THE USE OF
THE INVENTION OR LICENSED PRODUCTS.

         16.4     Nothing in this Agreement:

                  16.4.1   is a warranty or representation by Licensor as to the
                           validity or scope of any Licensor Patent Rights;

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -14-

<PAGE>

                  16.4.2   is a warranty or representation that anything made,
                           used, sold or otherwise disposed of under any license
                           granted in this Agreement is or will be free from
                           infringement of patents of third parties;

                  16.4.3   is an obligation to bring or prosecute actions or
                           suits against third parties for patent infringement
                           except as provided in Article 19;

                  16.4.4   confers by implication, estoppel or otherwise any
                           license or rights under any patents of Licensor other
                           than Licensor Patent Rights as defined in this
                           Agreement, regardless of whether those patents are
                           dominant or subordinate to Regent's Patent Rights; or

                  16.4.5   is an obligation to furnish any know-how not provided
                           in Regents' Patent Rights except as otherwise
                           required under this Agreement.

17.      PATENT PROSECUTION AND MAINTENANCE

         17.1     As long as Licensee has paid patent costs as provided for in
Paragraph 17.6, Licensor shall diligently endeavor to prosecute and maintain the
United States and foreign patents comprising Licensor Patent Rights, using
counsel of its choice selected from those approved by Licensee from the list
approved by Licensor. Licensor shall provide Licensee  with copies of all
relevant documentation so that Licensee may be informed of the continuing
prosecution and Licensee agrees to keep this documentation confidential.
Licensor's counsel will take instructions only from Licensor, considering input
from Licensee after these instructions have been approved in writing by
Licensor, and all patents and patent applications under this Agreement will be
assigned solely to Licensor.

         17.2     Licensor shall give thirty (30) days advance notice to
Licensee of any intention or decision to abandon or to otherwise cease
preparation, filing, prosecution or maintenance of any patent or patent
application relating to the Licensor Patent Rights (a "Proposed Discontinued
Patent"); provided, however, that abandonment of a patent application in favor
of a continuation or continuation-in-part thereof shall not constitute
discontinuance or abandonment of the parent application. In such case, Licensee
may elect at its sole discretion to cause Licensor to continue the preparation,
filing, prosecution or maintenance of the Proposed Discontinued Patent, so long
as Licensee agrees to pay all reasonable costs of Licensor in connection with
such preparation, filing, prosecution or maintenance at its sole expense.
Discontinuance may be on a country-by-country basis or for a patent application
or patent series in total.

         17.3     Licensor shall use all reasonable efforts to amend any patent
application to include claims reasonably requested by Licensee and to file
patent applications reasonably requested by Licensee to protect the products
contemplated to be sold under this Agreement.

         17.4     Licensee may apply for an extension of the term of any patent
included within Licensor Patent Rights, if appropriate. Licensee shall prepare
all documents, and UCSD agrees to execute the documents and to take additional
action as Licensee reasonably requests in connection therewith.

                                      -15-

<PAGE>

         17.5     If either party receives notice pertaining to infringement or
potential infringement of Licensor Patent Rights, that party shall notify the
other party within ten (10) days after receipt of notice of infringement, and
the terms of Paragraph 19 of this Agreement shall apply.

         17.6     Licensee shall reimburse UCSD for all the reasonable costs of
preparing, filing, prosecuting and maintaining all United States and foreign
patent applications contemplated by this Agreement and requested by Licensee.
Relevant costs billed by UCSD's counsel will be rebilled to Licensee and are due
within 30 days of rebilling by UCSD. These costs include: (a) patent prosecution
costs for the Invention incurred by UCSD prior to the execution of this
Agreement; (b) any patent prosecution costs that may be incurred for
patentability opinions, re-examination, re-issue, interferences, or inventorship
determinations; and (c) an additional amount equal to [*]% of the amount
properly billed to Licensee under this paragraph with respect to amounts
incurred by Licensor after the Effective Date. Prior costs relating to the
filing of patents requested by Licensee will be due ninety (90) days after
execution of this Agreement and billing by UCSD.

         17.7     Licensee may request Licensor to obtain patent or other patent
protection on the Invention or Licensor Patent Rights, as they relate to the
Field of Use in foreign countries, if" available, Licensor shall diligently
endeavor to obtain such patents or patent protection. If Licensee desires
Licensor to obtain such protection, Licensee shall notify Licensor of Licensee'
decision to have Licensor obtain or maintain foreign patents not less than sixty
(60) days prior to the deadline for any payment, filing, or action to be taken
in connection therewith. This notice concerning foreign filing must be in
writing, must identify the countries desired, and must reaffirm Licensee's
obligation to underwrite the costs thereof. The absence of such a notice from
Licensee to Licensor will be considered an election not to obtain or maintain
such foreign rights.

         17.8     Licensee's obligation to underwrite and to pay patent
prosecution costs will continue for so long as this Agreement remains in effect,
but Licensee may terminate its obligations with respect to any given patent
application or patent upon three (3) months written notice to UCSD. Licensor
will use its best efforts to curtail patent costs when a notice of termination
is received from Licensee. Licensor may prosecute and maintain such
application(s) or patent(s) at its sole discretion and expense, but Licensee
will have no further right or licenses thereunder. Non-payment of patent costs
may be deemed by UCSD as an election by Licensee not to the maintain
application(s) or patent(s) for which payment was not made, provided that UCSD
notifies Licensee in writing prior to the time UCSD ceases maintenance of any
patent or patent application and Licensee has not made payment within ten (10)
days after receipt of such notice.

         17.9     If Licensee terminates its obligation to pay patent
prosecution costs pursuant to Section 17.8, UCSD may, after notification of
Licensee, file, prosecute or maintain patent applications at its own expense in
any country in which Licensee has elected to terminate its payment obligation
pursuant to Section 17.8, and such applications and resultant patents will not
be subject to this Agreement.

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -16-

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18.      PATENT MARKING

         Licensee shall mark all Licensed Products made, used or sold under the
terms of this Agreement, or their containers, in accordance with the applicable
patent marking laws.

19.      PATENT INFRINGEMENT

         19.1     If Licensee learns of the substantial infringement of any
patent licensed under this Agreement, Licensee shall call UCSD's attention
thereto in writing and provide UCSD with reasonable evidence of infringement.
Neither party will notify a third party of the infringement of any of Licensor
Patent Rights without first obtaining consent of the other party, which consent
will not be unreasonably denied or delayed. Both parties shall use their best
efforts, including but not limited to arbitration, in cooperation with each
other to terminate infringement without litigation.

         19.2     Licensee may request that Licensor take legal action against
the infringement of Licensor Patent Rights. Request must be in writing and must
include reasonable evidence of infringement. If the infringing activity has
damaged or reasonably threatens to damage Licensee and has not abated within
seventy-five (75) days following the effective date of request, Licensor then
has the right to:

                  19.2.1   commence suit; or

                  19.2.2   refuse to participate in the suit.

UCSD shall give notice of Licensor's election in writing to Licensee by the end
of the seventy-fifth (75th) day after receiving notice of written request from
Licensee. Licensee may thereafter bring suit for patent infringement, at its own
expense, if and only if Licensor elects not to commence suit and if the
infringement occurred, at least in part, during the period and in a jurisdiction
where Licensee had exclusive rights under this Agreement. If Licensor elects to
commence suit, then Licensee may elect to share equally in the expense of such
litigation, subject to its right at any later time to discontinue sharing in the
expenses of the litigation. If, however, Licensee elects to bring suit in
accordance with this paragraph, Licensor may thereafter join that suit at its
own expense.

         19.3     Legal action as is decided on will be at the expense of the
party bringing suit (subject to the election of Licensee to share equally in the
expenses of the legal action as described above). Subject to Section 19.5, all
recoveries recovered thereby will be shared between Licensor and Licensee pro
rata in accordance with the expenses paid by each party in connection with the
litigation (expenses paid by Licensor pursuant to the last sentence of Section
19.2 shall not be included in the determination of the pro rata share).

         19.4     Each party shall reasonably cooperate with the other in
litigation proceedings instituted hereunder, but at the reasonable expense of
the party bringing suit. Litigation will

                                      -17-

<PAGE>

be controlled by the party bringing the suit, except that Licensor may be
represented by counsel of its choice and at its expense in any suit brought by
Licensee.

         19.5     Any recovery actually obtained by Licensee in a patent
infringement action against a third party in excess of litigation costs will,
only to the extent that such recovery is attributable to Devices,
Royalty-Bearing Products or Services sold by the third party infringer, be
shared with Licensor as follows:

         a)       any payment for past sales by the third party infringer of
Devices, Royalty-Bearing Products or Services will be deemed Net Sales and
Licensee will pay Licensor royalties thereon at the rates specified in Article
7.1.

         b)       any payment which covers future sales of Devices,
Royalty-Bearing Products or Services will be deemed a sublicense to a
partnership project, and monies will be shared as specified in Sections 5.6 and
5.7, to a maximum of $[*] per each infringer's infringing product or [*]% of the
total payments made by the third party infringer to Licensee in connection with
the litigation, whichever is the lesser.

         c)       Licensee and Licensor agree to negotiate in good faith
appropriate compensation to Licensor for any non-cash settlement or
cross-license settlement with an infringer; provided that (i) the compensation
shall only be provided to the extent such non-cash settlement or cross-license
settlement is attributable to the sale by the third party infringer of Devices,
Royalty-Bearing Products or Services; (ii) with respect to any non-cash or
cross-license settlement, Licensee shall pay to Licensor an amount equal to the
then fair market value of the non-cash or cross-license consideration received
by Licensee from the third party infringer.

         d)       Licensor will not share in any portion of the recovery by
Licensee that is payment for willful infringement or is not paid with respect to
the sale by the third party infringer of Devices, Royalty-Bearing Products or
Services.

20.      INDEMNIFICATION

         20.1     Licensee shall indemnify, hold harmless and defend Licensor,
its officers, employees, and agents; the sponsors of the research that led to
the Invention; and the inventors of the patents and patent applications in
Licensor Patent Rights and their employers against any and all claims, suits,
losses, damage, costs, fees, and expenses resulting from or arising out of
exercise of this license or any sublicense. This indemnification includes, but
is not limited to, any product liability, but shall exclude any breach of this
Agreement or any gross negligence or intentional misconduct by Licensor.

         20.2     Within ninety (90) days after the Effective Date, Licensee, at
its sole cost and expense, shall insure its activities in connection with the
work under this Agreement and obtain, keep in force and maintain insurance as
follows, or an equivalent program of self insurance:

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -18-

<PAGE>

         Comprehensive or commercial form general liability insurance
(contractual liability included) with limits as follows:

                  -        Each Occurrence $[*] (to be increased to $[*] at any
                           time when Licensee is conducting human clinical
                           trials)

                  -        Products/Completed Operations Aggregate $[*]

                  -        Personal and Advertising Injury $[*]

                  -        General Aggregate (commercial form only) $[*]

         The coverage and limits referred to under the above do not in any way
limit the liability of Licensee. Within ninety (90) days after the Effective
Date, Licensee shall furnish UCSD with certificates of insurance showing
compliance with all requirements. Certificates must:

                  -        Provide for thirty (30) day advance written notice to
                           UCSD and Stanford of any modification.

                  -        Indicate that UCSD and Stanford has been endorsed as
                           an additional Insured under the coverage referred to
                           under the above.

                  -        Include a provision that the coverage will be primary
                           and will not participate with nor will be excess over
                           any valid and collectable insurance or program of
                           self-insurance carried or maintained by UCSD and
                           Stanford.

         20.3     UCSD shall promptly notify Licensee in writing of any claim or
suit brought against ?? respect of which UCSD intends to invoke the
provisions of this Article. Licensee shall ?? UCSD informed on a current basis
of its defense of any claims under this Article.

21.      NOTICES

         Any ?? or payment required to be given to either party is properly
given and  effective on the ?? received. Notices shall be sent to the respective
addresses given below, or to another ?? as is designated by written notice given
to the other party.

In the case of Licensee:

                                    Cytokinetics, Incorporated
                                    2800 Sand Hill Road, Suite 250
                                    Menlo Park, CA 94025
                                    Attn: Dr. James Sabry, President and CEO

In the case of Licensor or UCSD:

                                    THE UNIVERSITY OF CALIFORNIA, SAN DIEGO
                                    Technology Transfer Office
                                    9500 Gilman Drive
                                    La Jolla, California 92093-0910

* Certain information on this page has been omitted and filed separately with
  the Commission. Confidential treatment has been requested with respect to the
  omitted portions.

                                      -19-

<PAGE>

                                    Attention: Director;
                                    Referring to: UCSD Case Nos. SD97-051,
                                    SD98-001, SD98-010, SD98-011

22.      ASSIGNABILITY

         This Agreement may be assigned by Licensor, but may be assigned by
Licensee only with the written consent of UCSD, which consent will not be
unreasonably withheld or delayed. Notwithstanding the foregoing, a merger or
sale of stock involving Licensee shall not be deemed to be an assignment of this
Agreement, and an assignment of this Agreement by Licensee in connection with a
sale of substantially all of Licensee's assets shall not require the consent of
UCSD. If Licensor assigns this Agreement, the assignee will agree in a written
agreement delivered to Licensee to be bound by the terms of this Agreement, and
Licensor shall continue to be bound by the terms of Articles 2 and 3, Section
16.1, Articles 17, 19, 21, 24, 25 and 30.

23.      NO WAIVER

         No waiver by either party of any default of this Agreement may be
deemed a waiver' of any subsequent or similar default.

24.      FAILURE TO PERFORM

         In either party finds it necessary to undertake legal action against
the other on account of failure of performance due under this Agreement, then
the prevailing party is entitled to reasonable attorney's fees in addition to
costs and necessary disbursements.

25.      GOVERNING LAWS

         THIS AGREEMENT WILL BE INTERPRETED AND CONSTRUED IN ACCORDANCE WITH THE
LAWS OF THE STATE OF CALIFORNIA, UNITED STATES OF AMERICA, WITH JURISDICTION IN
COURTS OF THE STATE OF CALIFORNIA, but the scope and validity of any patent or
patent application will be governed by the applicable laws of the country of
the patent or patent application.

26.      [Intentionally Omitted.]

27.      GOVERNMENT APPROVAL OR REGISTRATION

         If this Agreement or any associated transaction to which Licensee
becomes a party is required by the law of any nation to be either approved or
registered with any governmental agency, Licensee shall assume all legal
obligations to do so.

28.      EXPORT CONTROL LAWS

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<PAGE>

         Licensee shall observe all applicable United States and foreign laws
with respect to the transfer of Licensed Products and related technical data to
foreign countries, including, without limitation, the International Traffic in
Arms Regulations (ITAR) and the Export Administration Regulations. This may
include a requirement that Licensee manufacture in the United States Licensed
Products that are to be sold in the United States.

29.      SECRECY

         29.1     With regard to confidential information ("Data") supplied by
one party to another, which Data can be oral or written or both, both Licensee
and The Regents agree:

                  29.1.1    not to use the Data except for the sole purpose of
                  performing under the terms of this Agreement;

                  29.1.2   to safeguard Data against disclosure to others with
                  the same degree of care as it exercises with its own data of a
                  similar nature;

                  29.1.3   not to disclose Data to others (except by Licensee to
                  its actual or  prospective employees, agents, consultants,
                  contractors, investors, sublicensees, partners or regulatory
                  agencies who are bound to Licensee by a like obligation of
                  confidentiality) without the express written permission of the
                  other party (which shall not be unreasonably withheld or
                  delayed), except that neither party is prevented from using or
                  disclosing any of the Data that:

                           29.1.3.1 such party can demonstrate by written
                           records was previously known to it;

                           29.1.3.2 is now, or becomes in the future, public
                           knowledge other than through acts or omissions of
                           such party;

                           29.1.3.3 is lawfully obtained by Licensee from
                           sources independent of the other party; or

                           29.1.3.4 is required to be disclosed by law, court
                           order or process or by any governmental regulatory
                           body (including, without limitation, the United
                           States Securities and Exchange Commission); and

                  29.1.4   that the secrecy obligations of both parties with
                  respect to Data will continue for a period ending five (5)
                  years from the termination date of this Agreement.

         29.2     With regard to biological material received by Licensee from
The Regents or Stanford, if any, including any cell lines, vectors, genetic
material, derivatives, products, progeny or material derived therefrom
("Biological Material"), Licensee agrees:

                                      -21-

<PAGE>

                  29.2.1   not to use Biological Material except for the sole
                  purpose of performing under the terms of this Agreement;

                  29.2.2   not to transfer Biological Material to others (except
                  to its actual or prospective employees, agents, consultants,
                  contractors, investors, partners, sublicensees, agents or
                  regulatory agencies who are bound to Licensee by like
                  obligations conditioning and restricting access, use and
                  continued use of Biological Material, including appropriate
                  Material Transfer Agreements with Licensee) without the
                  express written permission of UCSD, UCSF or Stanford, except
                  that Licensee is not prevented from transferring Biological
                  Material that:

                           29.2.2.1 becomes publicly available other than
                           through acts or omissions of Licensee, or

                           29.2.2.2 is lawfully obtained by Licensee from
                           sources independent of The Regents or Stanford;

                  29.2.3   to safeguard Biological Material against disclosure
                  and transmission to others with the same degree of care as
                  it exercises with its own biological materials of a similar
                  nature;

                  29.2.4   to destroy all copies of Biological Material at the
                  termination of this Agreement.

30.      MISCELLANEOUS

         31.1     The headings of the several Paragraphs are inserted for
convenience of reference only and are not intended to be a part of or to affect
the meaning or interpretation of this Agreement.

         31.2     This Agreement is not binding on the parties until it has
been signed below on behalf of each party. It is then effective as of the
Effective Date.

         31.3     No amendment or modification of this Agreement is valid or
binding on the parties unless made in writing and signed on behalf of each
party.

         31.4     This Agreement embodies the entire understanding of the
parties and supersedes all previous communications, representations or
understandings, either oral or written, between the parties relating to the
subject matter hereof. The Secrecy Agreements referenced in Section 4 of the
recitals of this Agreement are hereby terminated.

         31.5     In case any of the provisions contained in this Agreement is
held to be invalid, illegal, or unenforceable in any respect, that invalidity,
illegality or unenforceability will cot affect any other provisions of this
Agreement, and this Agreement will be construed as if the invalid, illegal, or
unenforceable provisions had never been contained in it.

                                      -22-

<PAGE>

         IN WITNESS WHEREOF, both UCSD and Licensee have executed this
Agreement, in duplicate originals, by their respective and duly authorized
officers on the day and year written.

CYTOKINETICS, INCORPORATED              THE REGENTS OF THE UNIVERSITY
                                        OF CALIFORNIA

By: /s/ James Sabry                     By: /s/ Alan S. Paau
   ----------------------------            -------------------------------------
         (Signature)                                 (Signature)

Name: JAMES SABRY                       Name: Alan S. Paau
    ---------------------------
         Dr. James Sabry

Title: President and Chief              Title: Director,
       Executive Officer                Technology Transfer Office

Date: 5/4/98                            Date: 4/21/98

                                        THE BOARD OF TRUSTEES OF THE
                                        STANFORD JUNIOR UNIVERSITY

                                        By: The Regents of The University of
                                              California, as attorney-in-fact

                                              By: /s/ Alan S. Paau
                                                 -------------------------------

                                              Name: Alan S. Paau

                                              Title: Director, Technology
                                                     Transfer Office

                                              Date: 4/21/98

                 [SIGNATURE PAGE TO EXCLUSIVE LICENSE AGREEMENT]

                                      -23-