Document:

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                                                                   EXHIBIT 10.46

[***] CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY
BRACKETS, HAS BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
EXCHANGE COMMISSION PURSUANT TO RULE 24b-2 OF THE SECURITIES EXCHANGE ACT OF
1934, AS AMENDED.

                     COLLABORATION AND FACILITIES AGREEMENT

      THIS COLLABORATION AND FACILITIES AGREEMENT ("Agreement") is entered into
as of August 19, 2004 (the "Effective Date") by and between Portola
Pharmaceuticals, Inc., a Delaware corporation ("Portola"), and Cytokinetics,
Inc., a Delaware corporation ("Cytokinetics"). Portola and Cytokinetics may be
referred to individually as a "Party" or collectively as the "Parties".

                                    RECITALS

      A. WHEREAS, Portola subleases from Millennium Pharmaceuticals, Inc.
("Millennium"), certain space commonly known as 270 East Grand Avenue, South San
Francisco, California (the "Master Premises") pursuant to that certain Sublease
dated November 7, 2003 (the "Sublease"). Millennium leases the Master Premises
pursuant to that certain Lease, dated as of July 1, 2001 between Britannia
Pointe Grand Limited Partnership and COR Therapeutics, Inc. (the "Master
Lease"). A copy of the Sublease is attached hereto as EXHIBIT A. The Master
Premises are more particularly described therein.

      B. WHEREAS, Portola has capacity in its [***]facility and other laboratory
facilities, and personnel with appropriate expertise, within the Master Premises
to provide [***] and to conduct certain [***], [***] and [***] studies for drug
development.

      C. WHEREAS, Cytokinetics desires to have the right to use, under Portola's
supervision, portions of Portola's [***] facility and laboratory facility within
the Master Premises to conduct studies in connection with the Cytokinetics
research and development programs, and Cytokinetics desires to retain certain
Portola personnel to collaborate on such studies by providing certain technical
and scientific advice and services.

                                    AGREEMENT

      NOW, THEREFORE, in consideration of the covenants, terms, conditions and
agreements contained herein and in the related agreements described above, and
for other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, Portola and Cytokinetics hereby agree as follows:

      1. DEFINITIONS.

The following capitalized terms, when used in this Agreement in their singular
or plural forms, shall have the meanings ascribed to such terms in this Article
1. All capitalized terms used, but not defined in this Agreement shall have the
meanings given such terms in the Sublease.

            (a) "ADDITIONAL COSTS" means, for each month, the [***] cost of all
Additional Services provided during such month, but shall not include any costs
included in General Lab Operating Costs.

            (b) "ADDITIONAL SERVICES" has the meaning described in Section 4.

                                       1.

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            (c) "AFFILIATE" of a Party hereto means any person or entity
directly or indirectly controlling, controlled by, or under common control with
such Party. As used in this Section 1(d), "control" means that an entity owns,
directly or indirectly, more than fifty percent (50%) of the voting stock or
other ownership interest of another entity, or has the actual ability to control
and direct the management of another entity, whether by contract or otherwise.

            (d) "[***] COSTS" means, for each month, the actual direct cost of
all of the following for the [***] being used by Cytokinetics and Portola
pursuant to the Collaboration: [***] and [***]; [***] and [***]; reagents for
[***] instruments; preventative maintenance for [***] instruments; removal and
disposal of all [***] in compliance with all Hazardous Materials Laws; and
related supplies and disposables.

            (e) "COLLABORATION" means the studies and tasks that are described
in the Research Plan and are performed at the Licensed Premises.

            (f) "COLLABORATION MANAGER" has the meaning described in Section
3(f).

            (g) "COMMON AREAS" means the Master Premises' common entrances,
lobbies, restrooms, lunchrooms, elevators, stairways, hallways and other areas
used in common by the occupants of the Master Premises, but shall not include
the Lab Space.

            (h) "CONTROL" and cognates thereof mean, with respect to
information, know-how, methods, technologies and process development, and
modifications thereof, the possession of the ability to grant licenses or
sublicenses or to otherwise disclose, without violating the terms of any
agreement or other arrangement with, or the rights of, any Third Party.

            (i) "CYTOKINETICS RESEARCH AND DEVELOPMENT PROGRAMS" means research
and development activities that are directed towards the research and
development of therapeutics for the treatment of human diseases and conditions,
including but not limited to cancer, cardiovascular disease and fungal
infections, where such therapeutics have as their primary mode of action the
modulation of cytoskeletal function.

            (j) "CYTOKINETICS EQUIPMENT" means the equipment listed on EXHIBIT H
that Cytokinetics intends to move into the Licensed Premises during the Term to
be used in connection with the Collaboration.

            (k) "CYTOKINETICS INFORMATION" has the meaning described in Section
7.

            (l) "CYTOKINETICS MATERIALS" has the meaning described in Section
6(a).

            (m) "CYTOKINETICS PERSONNEL" means all employees, agents,
subcontractors, and representatives of Cytokinetics or Cytokinetics' Affiliates
who are involved in the Collaboration or otherwise have access to Portola
Information, but shall in no event be deemed to include Portola Personnel or
Portola's other agents, employees or contractors.

                                       2.

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            (n) "DIRECT [***] PURCHASES" means [***] percent ([***]%) of the
actual direct cost of all [***], other than [***], purchased by Portola at
Cytokinetics' written request for use by or on behalf of Cytokinetics pursuant
to the Collaboration.

            (o) "DIRECT CYTOKINETICS COSTS" means the cost of specific items
(e.g., Direct [***] Purchases, reagents, special [***], gases, equipment, etc.)
purchased at Cytokinetics' written request and used solely for the Collaboration
and/or by or on behalf of Cytokinetics in the Exclusive Space. Direct
Cytokinetics Costs shall exclude General [***] Purchases, [***] Costs, and
General Lab Operating Costs.

            (p) "EXCLUSIVE SPACE" has the meaning described in Section 3(a)(i).

            (q) "[***] PROGRAM" means any activities directed toward
identifying, discovering, developing or commercializing therapeutic products
that exert their primary effect by [***] the activity of the [***].

            (r) "FTE" means a full time dedicated scientific employee of
Portola, or if less than a full time dedicated scientific employee, a full time,
equivalent scientific employee year based upon a total of one thousand nine
hundred (1,900) working hours per year of scientific work, on or directly
related to the Collaboration carried out by an employee dedicated to work on the
studies and tasks that are described in the Research Plan, in each case, having
qualifications mutually agreed upon by the Parties.

            (s) "GENERAL [***] PURCHASES" means [***] percent ([***]%) of the
actual direct cost of all [***], in each case, purchased by Portola at
Cytokinetics' written request for use by or on behalf of Cytokinetics pursuant
to the Collaboration.

            (t) "GENERAL LAB OPERATING COSTS" means Portola's identifiable and
direct out-of-pocket costs of purchasing general laboratory supplies (including
reagents, kits, consumables, glassware and other laboratory supplies, but
excluding [***] Costs) during such month to maintain general inventories thereof
in the Lab Space.

            (u) "HAZARDOUS MATERIALS" means any material or substance that is
(i) defined, listed, or designated by any governmental agency as a "hazardous
substance", "hazardous material", "toxic substance", "extremely hazardous
substance", "hazardous waste," "biohazardous waste", "medical waste",
"radioactive waste", "extremely hazardous waste," "restrictive hazardous waste",
(ii) considered a waste, condition of pollution or nuisance under the Hazardous
Materials Laws; (iii) petroleum or a petroleum product or fraction thereof; (iv)
asbestos; and/or (v) substances known by the State of California to cause cancer
and/or reproductive toxicity.

            (v) "HAZARDOUS MATERIALS LAW" means any federal, state or local law,
statute, ordinance or regulation pertaining in any way to the environment,
pollution, the protection of health and safety, or Hazardous Materials,
including, without limitation, (i) the Comprehensive Environmental Response,
Compensation and Liability Act of 1980 ("CERCLA"), (ii) the Resource
Conservation and Recovery Act of 1976 ("RCRA"), (iii) California Health & Safety
Code Section 25100 et seq.; (iv) the California Safe Drinking

                                       3.

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Water and Toxic Enforcement Act of 1986; (v) the Federal Water Pollution Control
Act; (vi) California Water Code Section 1300 et seq., (vii) the Occupational
Safety & Health Act; (viii) the California Medical Waste Management Act, the
regulations promulgated pursuant to the foregoing, and all amendments and
modifications to any of the foregoing.

            (w) "LAB SPACE" has the meaning described in Section 3(a)(ii).

            (x) "LICENSED PREMISES" has the meaning described in Section 3(a).

            (y) "MAINTENANCE AND ADMINISTRATION COSTS" means Portola's
identifiable and direct out-of-pocket costs and expenses for: (i) equipment
repairs and maintenance; (ii) non-capital expensed equipment; (iii)
administrative supplies; (iv) copy, printing and graphic arts; (v)
postage/overnight delivery; (vi) consulting; and (vii) outside scientific
services.

            (z) "MASTER LEASE" has the meaning described in Recital A.

            (aa) "MASTER PREMISES" has the meaning described in Recital A.

            (bb) "PERSONAL PROPERTY" means the equipment and furniture existing
in the Licensed Premises. Personal Property shall not include Cytokinetics
Equipment.

            (cc) "[***] RESEARCH PROGRAM" means any activities directed toward
identifying, discovering, developing, or commercializing therapeutic products
that [***] or [***], other than by means of [***] the activity of [***] on its
[***]. Notwithstanding the foregoing, the [***] Research Program shall not
include any activities by Cytokinetics or Portola directed towards evaluating
Cytokinetics' potential therapeutic products (including, without limitation,
Cytokinetics compounds) that have as their primary mode of action the modulation
of cytoskeletal function in [***] screens to determine the effect of such
products on [***], including any effect on [***].

            (dd) "PORTOLA DRUG DEVELOPMENT PROGRAMS" means the [***] Research
Program, the [***] Program and the [***] Program.

            (ee) "PORTOLA INFORMATION" has the meaning described in Section 7.

            (ff) "PORTOLA PERSONNEL" means all employees, agents,
subcontractors, and representatives of Portola or Portola's Affiliates who are
involved in the Collaboration or otherwise have access to Cytokinetics
Information; provided, however, that for purposes of this Agreement, Charles
Homcy shall not be considered Portola Personnel with respect to any Services
provided to Cytokinetics by Charles Homcy that are governed by the terms of the
Consulting Agreement. For purposes of Section 1(ff), the term "Services" shall
have the meaning set forth in the Consulting Agreement dated March 3, 2003 (as
it may be amended from time to time) by and between Cytokinetics and Charles
Homcy (the "Consulting Agreement").

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                                       4.
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            (gg) "[***] PROGRAM" means any activities directed toward
identifying, discovering, developing or commercializing therapeutic products
that exert their primary effect by [***] the activity of the [***].

            (hh) "RESEARCH COMMITTEE" has the meaning described in Section 2(b).

            (ii) "RESEARCH PLAN" means, subject to Section 2(c), the research
plan attached as EXHIBIT E, as may be amended pursuant to the terms of this
Agreement, which shall govern the activities to be conducted by the Parties
pursuant to this Agreement in connection with the Cytokinetics Research and
Development Programs.

            (jj) "SPACE COSTS" means the identifiable and direct out-of-pocket,
third party operating costs and expenses actually and reasonably incurred by
Portola in operating the Exclusive Space and Lab Space for the Term, including
rent, property tax, insurance, landlord operating costs, utilities, building
service contracts and janitorial services (calculated on a pro rata basis to
reflect the portion of the square footage of the Exclusive Space and the Lab
Space relative to the total square footage of the Master Premises) listed on
EXHIBIT D hereto. The monthly amount of the rent portion of the Space Costs may
not exceed $[***] during the period from December 1, 2003 through [***] without
the prior written consent of Cytokinetics.

            (kk) "SUBLEASE" has the meaning described in Recital A.

            (ll) "SUPPORT COSTS" means an average monthly fee for [***] ([***])
Portola FTEs (whether or not such FTEs are [***] under the Collaboration)
working on the Collaboration as described in EXHIBIT D. "Support Costs" include
wages and other [***] that Portola [***] to pay [***] as described in EXHIBIT D,
but exclude [***] or other [***].

            (mm) "TERM" shall have the meaning set forth in Section 13(a).

            (nn) "THIRD PARTY" means any Party other than Portola, Cytokinetics
or their respective Affiliates.

      2. COLLABORATION.

            (a) GENERAL. The Parties shall conduct the Collaboration in
accordance with the Research Plan and the terms and conditions of this
Agreement. The goal of the Collaboration is for the Parties to conduct research
described in the Research Plan including studies examining [***], [***], [***],
and [***] associated with products being developed pursuant to the Cytokinetics
Research and Development Programs.

            (b) RESEARCH COMMITTEE. The Parties shall form a joint research
committee initially consisting of two (2) representatives designated by each
Party (the "Research Committee"). The initial Research Committee representatives
shall be [***] and [***] representing Cytokinetics and [***] and [***]
representing Portola. By mutual written agreement, the Parties may each add an
equal number of representatives to the Research Committee in response to the
Parties needing any additional expertise to perform their activities

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                                       5.
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under the Research Plan. Notwithstanding anything to the contrary herein,
Cytokinetics may, at its sole discretion, designate additional representatives
of Cytokinetics that may attend and participate in Research Committee meetings.
Each Party may replace its Research Committee representatives at any time upon
written notice to the other Party. Such representatives shall serve as the
primary contacts for their Party with regard to matters relating to the
Collaboration. The Research Committee shall provide a forum for the exchange of
information between the Parties regarding the progress of the Collaboration and
shall promote and facilitate communications between the Parties. The Research
Committee shall meet regularly, but not less than once each calendar month, and
at such times as shall be mutually agreed upon by the Parties. Each Research
Committee meeting shall be held in person at the Licensed Premises or at
Cytokinetics. Each Party's representatives of the Research Committee shall
collectively have one (1) vote on all matters to be decided by the Research
Committee, and with respect to matters regarding design of studies or direction
of research under the Collaboration for which the Research Committee is not able
to reach a unanimous decision, Cytokinetics will have the right, which it may
exercise in its sole discretion, to make the final decision on such matter. With
respect to matters regarding the allocation of resources and use of the Lab
Space for which the Research Committee is not able to reach a unanimous
decision, Portola will have the right, which it may exercise in its sole
discretion (subject to Section 3), to make the final decision on such matter.
Cytokinetics shall bear all expenses of the representatives on the Research
Committee related to their participation on the Research Committee and
attendance at Research Committee meetings in accordance with Section 4(b). The
Research Committee shall not amend or waive compliance with this Agreement.

            (c) RESEARCH PLAN. The Research Plan for the Term is set forth in
EXHIBIT E. If the Parties extend the Term, the Research Committee shall revise
the Research Plan by mutual written agreement of its representatives to account
for any changes to the Collaboration for the coming year, consistent with this
Section 2(c). The Research Committee may also revise the Research Plan during
the Term if the Research Committee determines in good faith that the goals of
the Research Plan are either being exceeded or are not being met. The Research
Plan will include activities that relate to the Cytokinetics Research and
Development Programs. In no event shall the Research Plan include any activities
that are included within the Portola Drug Development Programs. If the terms of
the Research Plan create any ambiguities with, or conflict with, the terms of
this Agreement, then the terms of this Agreement shall govern.

            (d) SCOPE OF SERVICES.

                  (i) Subject to the terms of this Agreement, Portola will
provide Cytokinetics with laboratory space for [***] ([***]) Cytokinetics
Personnel for the conduct of ongoing [***] work pursuant to the Cytokinetics
Research and Development Programs as set forth in Section 3 below. Such work
includes: (A) studies in which [***] and [***] measurements in [***] are made;
(B) studies on [***] and [***]; (C) studies on [***]; and (D) studies on [***]
and [***] using [***] to measure [***].

                  (ii) Subject to the terms of this Agreement, Portola will: (A)
provide Cytokinetics with [***], [***] and related support for the [***]
required for the studies described in Section 2(d)(i); and (B) make available to
the Cytokinetics Personnel the appropriate rooms

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                                       6.
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within Portola's [***] facility in the Master Premises for the conduct of [***]
with [***] as described in Section 3 below.

                  (iii) Subject to the terms of this Agreement, Portola agrees,
and shall ensure that the Portola Personnel complete diligently the obligations
of Portola as set forth in the Research Plan in accordance with the
specifications and timeframe specified therein; provided, however, that the
aggregate efforts of Portola Personnel under this Agreement shall not exceed an
average of [***] ([***]) FTEs per three (3) month period without the prior
written agreement of the Parties. If Portola can reasonably demonstrate to
Cytokinetics that the aggregate efforts of Portola Personnel under this
Agreement has exceeded an average of [***] ([***]) FTEs in a given quarter, the
Research Committee shall reasonably adjust the Research Plan to bring the
average number of Portola FTEs within the average of [***] ([***]) FTEs (for
such quarter and the subsequent quarter). As determined by the Research
Committee, certain Portola Personnel will attend and participate in various
meetings at Cytokinetics. Initially such Portola Personnel shall be limited to
[***] and [***]. Portola Personnel will report the results of their efforts
under the Collaboration to Cytokinetics in a timely manner using a mutually
agreed reporting format. In connection with the services performed hereunder,
Portola shall ensure that the Portola Personnel who perform such services shall
maintain laboratory notebooks, records and data ("Records") in accordance with
good laboratory and research practices. All Records shall be the sole property
of Cytokinetics, and shall be treated in all respects as Cytokinetics
Information, as provided for in Article 7. All Records shall be delivered to
Cytokinetics upon expiration or termination of this Agreement as provided for in
Article 14.

                  (iv) Portola shall not assign, delegate, or subcontract any of
the services under this Agreement without the prior written approval of
Cytokinetics. Any such approval shall not relieve Portola of its obligations
under this Agreement.

                  (v) During the Term, Portola shall not, and shall ensure that
the Portola Personnel shall not, conduct the services under this Agreement in
conjunction with any other services being conducted by Portola that would (a)
conflict with any of the provisions of this Agreement, or (b) preclude Portola
from complying with the provisions hereof.

                  (vi) PORTOLA'S PERFORMANCE OF THE COLLABORATION IS PROVIDED
WITHOUT ANY REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, INCLUDING WITHOUT
LIMITATION ANY IMPLIED WARRANTY OF SUCCESS OR THAT THE [***] OF [***] WILL NOT
[***] OR [***] ANY [***] OR OTHER [***] OF ANY [***].

                  (vii) Portola shall perform all of its obligations under the
Sublease (provided that the Sublease has not terminated due to Millennium's
default of the Sublease or the Master Lease) and shall not terminate or take any
action which could give rise to the right of Millennium to terminate the
Sublease, amend or waive any provision under the Sublease or make any elections,
exercise any right or remedy or give any approval under the Sublease that could
result in a substantial interference with Cytokinetics' use of the Licensed
Premises or Portola's performance of its obligations under this Agreement or
materially increase Cytokinetics'

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                                       7.
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obligations or decrease Cytokinetics' rights under this Agreement without, in
each instance, Cytokinetics' prior written consent.

                  (viii) Portola represents and warrants that: (a) the Sublease
is in full force and effect, and, to its knowledge, there exists under the
Sublease no default or event of default by either Millennium or Portola, nor has
there occurred any event which, with the giving of notice or passage of time or
both, could constitute such a default or event of default; and (b) the copy of
the Sublease attached to this Agreement is a true, correct and complete copy of
the Sublease.

      3. LICENSES.

            (a) Portola hereby grants to Cytokinetics, subject to the terms and
conditions of this Agreement: (i) a license in and to a portion of the Master
Premises consisting of approximately six hundred fifty (650) square feet of
laboratory space in Room G114 and G117 of the Master Premises (the "EXCLUSIVE
SPACE"); (ii) the right to use the [***] facility located within Rooms G127,
G129, G130, G131, G132, G134, G135, G136, G137, G138, G139, G141, G142, G143,
G144, G145, G146, G147, G148, G149, G150, G151, G152, G153, G154, G155 of the
Master Premises (collectively the "LAB SPACE"); (iii) a license to use the
Common Areas located in the Master Premises to the extent reasonably necessary
for Cytokinetics to utilize the Exclusive Space and the Lab Space; (iv) the
right of ingress to and egress from the Master Premises along existing
driveways, roads or paths; and (v) the right to use the Personal Property. The
Exclusive Space, the Lab Space and the Common Areas shall be collectively the
"LICENSED PREMISES". The Exclusive Space and the Lab Space are each depicted on
EXHIBIT B attached hereto and incorporated herein by this reference.
Cytokinetics' licenses and rights described in Sections 3(a)(ii)-(v) shall be
non-exclusive; provided, however, that Cytokinetics' license in Section 3(a)(i)
shall be exclusive to the extent Portola is able to provide exclusivity under
the Sublease. Portola shall provide electricity, water, heating, ventilating and
air conditioning to the Licensed Premises at the levels required for the uses
permitted herein.

            (b) Cytokinetics hereby expressly acknowledges and agrees to the
following: (i) the Licensed Premises shall not be used by Cytokinetics for any
purpose other than as allowed under the stricter of this Agreement or the
Sublease, and that Cytokinetics shall use the Licensed Premises in full
compliance with the restrictions of the stricter of this Agreement or the
Sublease; (ii) Cytokinetics Personnel shall not enter any portion of the Master
Premises other than the Licensed Premises; (iii) Portola shall have priority
access to, and use of, the Lab Space, and Cytokinetics shall have access to the
Lab Space on an "as available" basis, provided that Portola shall use reasonable
efforts to accommodate Cytokinetics' need for such Lab Space and Cytokinetics
shall have the right to use the portions of the Lab Space designated by
Cytokinetics not less than fifteen (15) full business days each calendar
quarter; (iv) Cytokinetics has no right, title or interest in or to any of the
Licensed Premises other than as expressly set forth herein and that the license
hereby granted does not grant an estate in the Licensed Premises; (v)
Cytokinetics shall not allow more than [***] ([***]) Cytokinetics Personnel in
the Licensed Premises at any single time; and (vi) Cytokinetics shall allow only
Cytokinetics Personnel into the Licensed Premises and shall not allow any
invitees into the Licensed Premises without prior notice to Portola. Portola
shall not enter, and shall prevent its employees, agents and contractors from
entering, the Exclusive Space except as required to perform its obligations
under this

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                                       8.
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Agreement as provided herein or except as required under the Sublease. Portola,
except in the case of emergency or except as required under the Sublease, shall
provide Cytokinetics with one (1) business day notice prior to entry of the
Exclusive Space. Portola shall use commercially reasonable efforts so that any
entry by Portola: (x) shall not impair Cytokinetics' operations more than
reasonably necessary; and (y) shall comply with Cytokinetics' reasonable
security measures.

            (c) Cytokinetics may use the Exclusive Space twenty-four (24) hours
per day, seven (7) days per week. Cytokinetics may use the Lab Space from 8:00
am until 6:00 pm, Monday through Friday (collectively, "Business Hours") without
Portola's prior permission. Cytokinetics may only use the Lab Space outside
Business Hours with Portola's prior verbal or written permission, which
permission shall not be unreasonably withheld or delayed. Cytokinetics agrees
that the use of the Licensed Premises by Cytokinetics Personnel shall not
interfere with Portola's use of the Master Premises (other than the Exclusive
Space and reasonable interference caused by Cytokinetics' use of the balance of
the Licensed Premises in accordance with this Agreement) or any other tenant's
use of the Master Premises (other than the Exclusive Space and reasonable
interference caused by Cytokinetics' use of the balance of the Licensed Premises
in accordance with this Agreement).

            (d) The licenses granted herein for Cytokinetics' use of the
Licensed Premises shall be subject to commercially reasonable rules and
regulations as may be imposed by Portola from time to time for the joint use of
the Master Premises or for purposes of safety, security and protection of
proprietary information. The current rules and regulations are attached hereto
as EXHIBIT C. Notwithstanding the foregoing, Cytokinetics shall not be required
to comply with any new rule or regulation unless the same applies
non-discriminatorily to all occupants of the Master Premises, does not
unreasonably interfere with Cytokinetics' use of the Licensed Premises and does
not materially increase the obligations or decrease the rights of Cytokinetics
under this Agreement.

            (e) During the term of this Agreement, Cytokinetics shall not make
any alterations or improvements to the Licensed Premises or the Master Premises
without the prior written consent of Portola, which consent may be withheld in
Portola's sole and absolute discretion. Notwithstanding the foregoing,
Cytokinetics shall have the right to install data and telecommunications cabling
and the Cytokinetics Equipment subject to the reasonable approval of Portola and
to the terms and conditions of the Sublease.

            (f) Cytokinetics shall appoint [***] to act as its "COLLABORATION
MANAGER". The Collaboration Manager shall ensure that the terms of this
Agreement are communicated to, explained and understood by, and complied with by
all Cytokinetics Personnel. In addition, the Collaboration Manager shall monitor
and manage the manner and level of usage of Portola resources by Cytokinetics,
including the additional services set forth in Section 4(b) below. The
Collaboration Manager will be Portola's point of contact at Cytokinetics with
whom Portola shall communicate any concerns with respect to Cytokinetics'
obligations under this Agreement. Cytokinetics may replace its Collaboration
Manager at any time upon written notice to Portola. The Research Committee
representatives representing Portola shall meet regularly, but not less than
once each week, and at such times as shall be

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                                       9.
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mutually agreed upon by the Parties, with the Collaboration Manager at the
Licensed Premises or at Cytokinetics.

            (g) Notwithstanding anything to the contrary contained herein,
neither Party shall have any obligation under this Agreement unless and until
the consent of the Landlord (as defined in the Master Lease) or Millennium
Pharmaceuticals, Inc., if required, in form reasonable satisfactory to
Cytokinetics (which form shall include a waiver of subrogation in favor of
Cytokinetics) shall have been obtained in accordance with the Sublease. Portola
shall use commercially reasonable efforts to obtain such consents as soon as
reasonably practicable. If Portola fails to obtain such consents within thirty
(30) days after execution of this Agreement by Cytokinetics, then either Party
may terminate this Agreement by giving the other Party written notice thereof.

      4. LICENSE FEES AND COSTS.

            (a) Following each month of the Term, Portola shall invoice
Cytokinetics for the applicable Space Costs, Support Costs, General Lab
Operating Costs, Maintenance and Administration Costs, General [***] Purchases,
[***] Costs, Direct Cytokinetics Costs and Additional Costs for such month. The
Space Costs, General [***] Purchases, Support Costs, General Lab Operating
Costs, Maintenance and Administration Costs, [***] Costs and Additional Costs
are collectively referred to throughout this Agreement as the "LICENSE FEE".
Cytokinetics shall pay to Portola the License Fee and Direct Cytokinetics Costs
set forth in each such correct invoice on a monthly basis within thirty (30)
days of its receipt thereof or the end of the applicable month, whichever is
later; provided, however, that Cytokinetics shall not be required to pay Portola
any License Fees for a given calendar quarter in excess of [***] percent
([***]%) of the amounts specified for the given calendar quarter in the
spreadsheets attached to EXHIBIT D without the prior written consent of
Cytokinetics. Cytokinetics shall have the right at its expense, exercisable upon
reasonable prior written notice to Portola, on a quarterly basis, and in any
event on or after [***], to inspect at Portola's office during normal business
hours Portola's records as they relate to the costs comprising the License Fee
and Direct Cytokinetics Costs. Portola shall refund to Cytokinetics any
overpayment identified by such inspection within thirty (30) days of request by
Cytokinetics. A complete breakdown of the License Fee is set forth on EXHIBIT D
attached hereto and incorporated herein by this reference. Cytokinetics
acknowledges and agrees that fees for some components of the License Fee are
variable and may be adjusted from time to time with prior written consent from
Cytokinetics. The License Fee and Direct Cytokinetics Costs shall be payable,
without demand (other than the invoice described in this Section 4) or offset,
in lawful money of the United States. If this Agreement terminates or expires on
any date which is not the first day of a calendar month, the License Fee payable
for such month shall be prorated based on the number of days in the applicable
calendar month. Any expenditure included in the License Fee shall be limited to
the lesser of the actual amount incurred or the fair market value of the goods
and services involved, shall be reasonably incurred, and shall be substantiated
by documentary evidence available for inspection and review by Cytokinetics.
Notwithstanding anything to the contrary herein, if all or any part of the
Licensed Premises or the Personal Property should become not reasonably suitable
for Cytokinetics' use as a consequence of casualty, cessation of utilities or
other services, interference with access to the Licensed Premises, legal
restrictions or the presence of any Hazardous Material which does

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                                      10.
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   not result from Cytokinetics' release or emission of such Hazardous Material,
   and in any of the foregoing cases the interference with Cytokinetics' use of
   the Licensed Premises or the Personal Property persists for three (3) days,
   then Cytokinetics shall be entitled to an equitable abatement of the License
   Fee to the extent of the interference.

At the costs set forth in EXHIBIT D, Portola agrees to provide to Cytokinetics
the following services in connection with activities performed pursuant to the
Agreement ("Additional Services"):

                  (i) Shipping and receiving.

                  (ii) Glass washing and sterilization, if needed, up to a
maximum of sixteen (16) hours each month.

                  (iii) Procuring, managing and storing in compliance with
Hazardous Materials Law: (1) [***], [***], and [***] as required by the
Collaboration; (2) [***] (including 5% [***] and [***], and 100% [***]) as
required by the Collaboration; and (3) all materials used by Portola Personnel
in connection with the Collaboration including those listed on EXHIBIT G.

                  (iv) Compliance with all aspects of a hazardous waste
management program to address waste Hazardous Materials generated as a result of
the Collaboration.

                  (v) Collection, storage, and disposal of all waste Hazardous
Materials generated as a result of the Collaboration in compliance with all
Hazardous Materials Laws.

                  (vi) Occupational health and safety training to Cytokinetics
Personnel and Portola Personnel as required by Hazardous Materials Laws in
connection with the Collaboration, including but not limited to hazard
communication training, radiation training, injury illness and prevention,
biohazard training, respiratory protection training, and California Safe
Drinking Water and Toxic Enforcement Act (Proposition 65) training.

                  (vii) Facilities support, including repair and maintenance of
the Personal Property, water systems, HVAC and electrical systems, up to a
maximum of ten (10) hours each month.

                  (viii) Access and use of telephone system.

                  (ix) Building security services.

            (b) Cytokinetics shall promptly reimburse Portola for all
identifiable and direct out-of-pocket business expenses (including without
limitation costs of travel, lodging, and meals) actually incurred by the Portola
Personnel for services not otherwise covered by this Agreement, so long as such
expenses are reasonable and requested by Cytokinetics in writing. Portola shall
maintain adequate books and records relating to any such expenses to be
reimbursed and shall submit requests for reimbursement within thirty (30) days
and in a form acceptable to Cytokinetics.

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                                      11.
<PAGE>

            (c) Upon the Effective Date, Cytokinetics shall pay Portola the
amount of $[***] as an upfront fee for all invoices owed to Portola by
Cytokinetics for Portola's participation in the Collaboration from December 1,
2003 up through the Effective Date. For any invoices owed to Portola by
Cytokinetics under this Agreement after the Effective Date, Cytokinetics will
pay Portola a late payment fee of [***] percent ([***]%) per month for any
invoice that is thirty (30) days past due.

      5. INTELLECTUAL PROPERTY AND INVENTIONS.

            (a) EXISTING PROPRIETARY RIGHTS.

                  (i) CYTOKINETICS TECHNOLOGY. Portola agrees and acknowledges
that Portola shall acquire no rights of any kind whatsoever with respect to any
patents, copyrights, trademarks, trade secrets or other proprietary rights of
Cytokinetics existing as of December 1, 2003 as a result of Portola's
performance under this Agreement or otherwise, except for a nonexclusive right
of Portola to utilize such proprietary rights of Cytokinetics for the sole
purpose of, and to the extent necessary for, performing the Research Plan during
the Term.

                  (ii) PORTOLA TECHNOLOGY. Cytokinetics agrees and acknowledges
that Cytokinetics shall acquire no rights of any kind whatsoever with respect to
any patents, copyrights, trademarks, trade secrets, know-how or other
proprietary rights of Portola existing as of December 1, 2003 as a result of
Cytokinetics' performance under this Agreement or otherwise, except for the
nonexclusive Background License set forth in this Section 5(a)(ii). Portola
hereby grants to Cytokinetics a worldwide, transferable, royalty-free,
irrevocable, perpetual license (with the right to grant and authorize
sublicenses) under the Background Technology to make, use, have made, sell,
offer for sale, import, reproduce, prepare derivative works of, or otherwise to
practice, exploit and commercialize products that arise out of the performance
of the Cytokinetics Research and Development Programs (the "Background
License"). "Background Technology" means: (1) (a) the information, know-how,
methods, and technologies, and modifications thereof, and all intellectual
property rights therein, that are Controlled by Portola either as of December 1,
2003, or Controlled thereafter at any time during the Term, that are necessary
for and either actually disclosed by Portola pursuant to, or used by Portola in
performing under, the Research Plan; and (2) to the extent not otherwise
included in (1), the Portola Inventions. For avoidance of doubt, Background
Technology shall be Portola Information, which Cytokinetics may disclose to the
extent necessary to practice the Background License and otherwise as permitted
in Section 7.

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                                      12.
<PAGE>

            (b) INVENTIONS UNDER THIS AGREEMENT.

                  (i) GENERAL PRINCIPLES. Cytokinetics shall own all right,
title and interest in and to any and all inventions, works of authorship, ideas
or information developed, created or conceived in the course of the performance
of the Research Plan that are not Portola Inventions, and all intellectual
property rights therein ("Inventions"). Portola shall own all right, title and
interest in all Portola Inventions (as defined below). "Portola Inventions"
means any and all inventions, works of authorship, ideas or information
developed, created, or conceived by Portola Personnel, with or without
Cytokinetics assistance or contribution, in the course of the performance of the
Research Plan that are necessary to perform [***], [***] or [***] in the [***]
performed pursuant to the Research Plan.

                  (ii) INVENTIONS RELATING TO CYTOKINETICS RESEARCH AND
DEVELOPMENT PROGRAMS. Portola shall and hereby does assign to Cytokinetics all
of Portola's right, title and interest in and to all Inventions. Cytokinetics
shall and hereby does assign to Portola all of Cytokinetics' right, title and
interest in and to all Portola Inventions.

                  (iii) PATENT FILING AND PROSECUTION. Cytokinetics shall have
the right, but not the obligation, to file, prosecute and maintain patent
applications and patents on all Inventions. Portola shall have the right, but
not the obligation, to file, prosecute and maintain patent applications and
patents on all Portola Inventions. Portola will not file, under any
circumstances, a patent application in any country in the world claiming any
composition of matter, use, formulation, synthetic procedure, manufacturing
procedure or method of administration that is Cytokinetics Information and/or
Cytokinetics Materials without Cytokinetics' prior written consent. Cytokinetics
will not file, under any circumstances, a patent application in any country in
the world claiming any composition of matter, use, formulation, synthetic
procedure, manufacturing procedure or method that is Portola Information without
Portola's prior written consent.

            (c) FURTHER ACTS. Each Party shall perform such additional actions
necessary to affect the intent of Section 5(b), and shall reasonably cooperate
with the other Party in doing so.

      6. CYTOKINETICS MATERIALS.

            (a) Cytokinetics will transfer to Portola reasonable quantities of
any materials to be tested and/or utilized under the Research Plan, and such
additional materials as Cytokinetics and Portola may from time-to-time agree
during the Term (such materials, together with any derivatives, progeny, or
improvements developed therefrom, and any combination of the foregoing with
other substances, referred to as "Cytokinetics Materials") for the sole purpose
of performing the Research Plan.

            (b) Cytokinetics shall retain all right, title and interest in and
to the Cytokinetics Materials, except for the sole purposes of, and to the
extent necessary for Portola Personnel to perform the Research Plan during the
Term. Nothing herein shall be construed (i) to prevent Cytokinetics at any time
from using or disclosing the Cytokinetics Materials, (ii) as a grant by
Cytokinetics to Portola of any license, joint venture, partnership or other

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<PAGE>

ownership interest in or to the Cytokinetics Materials, or (iii) to obligate
Cytokinetics to enter into any further agreement with Portola relating to the
Cytokinetics Materials.

            (c) The Cytokinetics Materials shall be used only for the conduct of
the services under the Agreement, and not for any other study or purpose without
the prior written consent of Cytokinetics. Portola agrees to retain control over
the Cytokinetics Materials and not to transfer Cytokinetics Materials to any
other person or entity other than those working on the services under the
Agreement, without the prior written consent of Cytokinetics. Under no
circumstances shall Portola undertake any efforts (including but not limited to
NMR, UV, IR, x-ray crystallography and mass spectroscopy and similar analyses)
to ascertain the structure of any Cytokinetics Materials provided hereunder
without the prior written consent of Cytokinetics. Portola shall not reverse
engineer, disassemble or decompile any Cytokinetics Materials or any other
composition, software or other items which are provided to Portola in connection
with the Cytokinetics Materials.

            (d) The Cytokinetics Materials will be used only in vitro or in
[***], and not for human clinical testing. Any [***] any of the Cytokinetics
Materials in the course of investigations or products derived from such [***]
will not be used for [***] purposes at any time.

            (e) Portola acknowledges that the Cytokinetics Materials are
experimental in nature and may have unknown characteristics and therefore agrees
to use prudence and reasonable care in the use, handling, storage,
transportation and disposition and containment of Cytokinetics Materials.
Portola acknowledges that all services conducted utilizing the Cytokinetics
Materials will be conducted under suitable containment conditions and in
accordance with existing laws and regulations including Hazardous Materials
Laws.

            (f) Any and all unused Cytokinetics Materials will promptly be
returned to Cytokinetics upon request.

            (g) The Cytokinetics Materials are being made available in order to
conduct further research concerning them. THE CYTOKINETICS MATERIALS BEING
SUPPLIED UNDER THIS AGREEMENT ARE BEING SUPPLIED "AS IS", WITH NO WARRANTIES,
EXPRESS OR IMPLIED, AND CYTOKINETICS EXPRESSLY DISCLAIM ANY WARRANTY OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NONINFRINGEMENT OF ANY
INTELLECTUAL PROPERTY RIGHTS OF ANY THIRD PARTY. Cytokinetics disclaims all
representations that use of Cytokinetics Materials by Portola will not infringe
any patent or other proprietary right of any third party.

      7. CONFIDENTIALITY.

            (a) PORTOLA INFORMATION. The Parties acknowledge that, in the course
of the Collaboration at the Licensed Facilities, Cytokinetics and Cytokinetics
Personnel may receive, observe, and otherwise have access to Portola
Information. Cytokinetics and Portola agree to use commercially reasonable
efforts to limit the extent to which Cytokinetics Personnel have access to
Portola Information, but the Parties acknowledge and agree that Cytokinetics

                                      14.

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<PAGE>

Personnel may obtain such information in good faith by reason of the Parties'
activities under this Agreement. For purposes of this Agreement the term
"Portola Information" means any information disclosed to Cytokinetics by or on
behalf of Portola or its Affiliates (including any such information disclosed in
the course of the Parties' participation in the Collaboration from December 1,
2003 up through the Effective Date), either directly or indirectly in writing,
graphically, electronically, orally or by inspection of tangible objects,
including without limitation any compound, extract, media, vector, gene,
protein, sequence, cell, cell line, formulation, sample or other composition,
including any structural information and/or any methods of synthesis relating to
the foregoing; any assay, procedure, algorithm, software program, discovery,
Portola Invention, model, formula, data, result, idea or technique; any trade
secret, trade dress, copyright, patent or other intellectual property right, or
any registration or application therefor, or materials relating thereto; and any
information relating to any of the foregoing or to any research, development,
purchasing, manufacturing, engineering, marketing, servicing, sales, financing,
legal or other business or corporate financial activities or to any present or
future products, design details and specifications, prices, plans, forecasts,
suppliers, clients, customers, employees, consultants or investors. Portola
Information also includes, without limitation, any information that Portola
discloses to Cytokinetics that Portola has received from a Third Party which
Portola is obligated to treat as confidential or proprietary. For clarity,
Portola Inventions shall be deemed Portola Information.

Specific aspects or details of Portola Information will not be deemed to be
within the public knowledge or in the prior possession of Cytokinetics merely
because the aspects or details of the Portola Information are embraced by
general disclosures in the public domain or in the prior possession of
Cytokinetics. In addition, any combination of Portola Information will not be
considered in the public knowledge or in the prior possession of Cytokinetics
merely because individual elements thereof are in the public domain or in the
prior possession of Cytokinetics, unless the combination are in the public
knowledge or in the prior possession of Cytokinetics.

                  (i) CONFIDENTIALITY AND NON-USE OBLIGATIONS. Cytokinetics
shall hold all Portola Information in strict confidence and shall not disclose
or otherwise make available Portola Information to any Third Party except
Cytokinetics' collaborators or bona fide potential collaborators who are bound
by written agreement providing an obligation of confidentiality thereto and
restriction on use and disclosure thereof commensurate in scope with those
provided in this Agreement, and Cytokinetics shall restrict access to Portola
Information to those Cytokinetics Personnel who have a need to know such
information in order to exercise Cytokinetics' rights and to perform
Cytokinetics' obligations under this Agreement. Cytokinetics shall not use,
reproduce, or exploit Portola Information for any purpose other than for
exercising its rights and performing its obligations under this Agreement.
Except for the license granted in Section 5 of this Agreement, Cytokinetics
shall have no right, title, or interest of any nature in any Portola
Information. Cytokinetics shall not have any obligations under this Agreement
with respect to any portion of the Portola Information for which Cytokinetics
can demonstrate by competent written proof: (a) is now, or hereafter becomes,
through no act or failure to act on the part of Cytokinetics, generally known or
available in the public domain; (b) is known by Cytokinetics at the time of
receiving such information, from Portola hereunder; (c) is hereafter furnished
to Cytokinetics by a Third Party who does not have an obligation to Portola with
respect thereto; (d) is independently developed by or on behalf of Cytokinetics
without the

                                      15.
<PAGE>

aid, use or application of Portola Information; or (e) is the subject of a
written permission to disclose provided by Portola. Notwithstanding anything to
the contrary herein, upon Portola's consent, which shall not be unreasonably
withheld or delayed, Cytokinetics may disclose the Portola Information,
including Portola Inventions as it deems, in its sole discretion, necessary to
file patent applications in any country in the world claiming composition of
matter, use, formulation, synthetic procedure, manufacturing procedure or method
that is an Invention hereunder.

                  (ii) FURTHER OBLIGATIONS. Cytokinetics shall ensure that all
Cytokinetics Personnel who work at the Licensed Premises or who shall otherwise
receive disclosure of Portola Information have signed nondisclosure agreements
with confidentiality and non-use provisions at least as restrictive as those in
this Agreement.

                  (iii) PERMITTED USES. Notwithstanding any other provision of
this Agreement, disclosure of Portola Information shall not be precluded to the
extent such disclosure:

                        (1) is in response to a valid order of a court or other
governmental body of a country or any political subdivision thereof; provided,
however, that Cytokinetics shall first have given notice to Portola and shall
have made a reasonable effort to obtain a protective order requiring that the
Portola Information so disclosed be used only for the purposes for which the
order was issued;

                        (2) is otherwise required by law or regulation; provided
that Cytokinetics shall give notice to Portola and shall make a reasonable
effort to obtain a protective order requiring that the Portola Information so
disclosed be used only for the purposes for which the law or regulation
required; or

                        (3) is otherwise necessary to establish rights or
enforce obligations under Article 5 of this Agreement, but only to the extent
that any such disclosure is necessary for such purpose.

                  (b) CYTOKINETICS INFORMATION. The Parties acknowledge that, in
the course of the Collaboration, Portola and Portola Personnel may receive,
observe, and otherwise have access to Cytokinetics Information. For purposes of
this Agreement the term "Cytokinetics Information" means any information
disclosed to Portola by or on behalf of Cytokinetics (including any such
information disclosed in the course of the Parties' participation in the
Collaboration from December 1, 2003 up through the Effective Date), either
directly or indirectly in writing, graphically, electronically, orally or by
inspection of tangible objects, or which Portola generates in the performance of
the Research Plan on behalf of Cytokinetics under this Agreement, including
without limitation any compound, extract, media, vector, gene, protein,
sequence, cell, cell line, formulation, sample or other composition, including
any structural information and/or any methods of synthesis relating to the
foregoing; any assay, procedure, algorithm, software program, discovery,
Inventions, model, formula, data, result, idea or technique; any trade secret,
trade dress, copyright, patent or other intellectual property right, or any
registration or application therefor, or materials relating thereto; and any
information relating to any of the foregoing or to any research, development,
purchasing, manufacturing,

                                      16.
<PAGE>

engineering, marketing, servicing, sales, financing, legal or other business or
corporate financial activities or to any present or future products, design
details and specifications, prices, plans, forecasts, suppliers, clients,
customers, employees, consultants or investors. Cytokinetics Information also
includes, without limitation, any information disclosed by Cytokinetics to
Portola that Cytokinetics has received from a Third Party which Cytokinetics is
obligated to treat as confidential or proprietary. For clarity, any data,
methods, results, conclusions, information and/or other deliverables made,
conceived, reduced to practice or otherwise generated in connection with the
performance of the Research Plan under this Agreement, whether solely by
Cytokinetics, jointly by Cytokinetics and Portola Personnel, or solely by the
Portola Personnel, that are not Portola Inventions, shall be deemed Cytokinetics
Information.

                  (i) CONFIDENTIALITY AND NON-USE OBLIGATIONS. Portola shall
hold all Cytokinetics Information in strict confidence and shall not disclose or
otherwise make available Cytokinetics Information to any Third Party, and
Portola shall restrict access to Cytokinetics Information to those of its
employees who have a need to know such information in order to perform the
services under this Agreement. Portola shall not use, reproduce, or exploit
Cytokinetics Information for any purpose other than exercising its rights and
performing its obligations under this Agreement; otherwise, Portola shall have
no right, title, or interest of any nature in any Cytokinetics Information.
Portola shall not have any obligations under this Agreement with respect to any
portion of the Cytokinetics Information for which Portola can demonstrate by
competent written proof: (a) is now, or hereafter becomes, through no act or
failure to act on the part of Portola, generally known or available in the
public domain; (b) is known by Portola at the time of receiving such
information, from Cytokinetics hereunder; (c) is hereafter furnished to Portola
by a Third Party who does not have an obligation to Cytokinetics with respect
thereto; (d) is independently developed by or on behalf of Portola without the
aid, use or application of Cytokinetics Information; or (e) is the subject of a
written permission to disclose provided by Cytokinetics.

Specific aspects or details of Cytokinetics Information will not be deemed to be
within the public knowledge or in the prior possession of Portola merely because
the aspects or details of the Cytokinetics Information are embraced by general
disclosures in the public domain or in the prior possession of Portola. In
addition, any combination of Cytokinetics Information will not be considered in
the public knowledge or in the prior possession of Portola merely because
individual elements thereof are in the public domain or in the prior possession
of Portola, unless the combination are in the public knowledge or in the prior
possession of Portola. With respect to Cytokinetics Information which arises
under the Research Plan, Portola must establish that the exception (b) applies
by virtue of written documentation that Portola receives or obtains from a Third
Party rather than in reliance on its own internally generated written
documentation.

                  (ii) FURTHER OBLIGATIONS. Portola shall ensure that each
Portola Personnel who performs work at the Licensed Premises pursuant to the
Collaboration or shall otherwise receive disclosure of Cytokinetics Information
has signed nondisclosure agreements with confidentiality and non-use provisions
at least as restrictive as those in this Agreement.

                  (iii) PERMITTED USES. Notwithstanding any other provision of
this Agreement, disclosure of Cytokinetics Information shall not be precluded to
the extent such disclosure:

                                      17.
<PAGE>

                        (1) is in response to a valid order of a court or other
governmental body of a country or any political subdivision thereof; provided,
however, that Portola shall first have given notice to Cytokinetics and shall
have made a reasonable effort to obtain a protective order requiring that the
Cytokinetics Information so disclosed be used only for the purposes for which
the order was issued;

                        (2) is otherwise required by law or regulation; provided
that Portola shall give notice to Cytokinetics and shall make a reasonable
effort to obtain a protective order requiring that the Cytokinetics Information
so disclosed be used only for the purposes for which the law or regulation
required; or

                        (3) is otherwise necessary to establish rights or
enforce obligations under Article 5 of this Agreement, but only to the extent
that any such disclosure is necessary for such purpose.

            (c) PERMITTED DISCLOSURES. Notwithstanding anything to the contrary,
the confidentiality obligations contained in this Article 7 shall not apply to
any Portola Information or Cytokinetics Information (collectively, the
"Confidential Information") disclosed by one Party (the "Disclosing Party") to
the other Party (the "Receiving Party") solely to the extent that the Receiving
Party is required either to disclose such Confidential Information by law, order
or regulation of a governmental agency or a court of competent jurisdiction, or
to disclose Confidential Information to any governmental agency for purposes of
obtaining approval to test or market a product, provided in either case that the
Receiving Party shall, to the extent it may legally do so, provide written
notice thereof to the Disclosing Party and reasonable opportunity to object to
any such disclosure or to request confidential treatment thereof, and shall use
reasonable efforts to secure confidential treatment of or a protective order for
the Confidential Information so required to be disclosed.

      8. COMPLIANCE WITH PERMITS; HAZARDOUS MATERIALS.

            (a) Cytokinetics shall comply with all conditions of any and all
permits, licenses and other governmental and regulatory approvals held by
Portola with respect to its use of the Licensed Premises, including those
covering [***] use and the discharge of appropriately treated materials or
wastes into or through any sanitary or storm sewer serving the Master Premises.
Cytokinetics will not cause any Hazardous Materials to be brought upon, kept or
used in or about the Licensed Premises by Cytokinetics Personnel, except for
those listed on EXHIBIT F or other materials commonly used in connection with
the business operations allowed by this Agreement and conducted on the Licensed
Premises and then, in full compliance with Hazardous Materials Laws and the
Sublease. Cytokinetics agrees to promptly notify Portola of the amount and type
of any Hazardous Materials other than those used on EXHIBIT F to be brought
upon, kept or used in or about the Licensed Premises by Cytokinetics.

            (b) Notwithstanding the foregoing, if Hazardous Materials are
discharged or released by Cytokinetics Personnel in violation of Hazardous
Materials Laws, then Cytokinetics shall indemnify, defend (with counsel approved
by Portola) and hold Portola harmless from and against any and all claims,
judgments, damages, penalties, fines, costs, liabilities and losses which arise
during or after the term of this Agreement as a result of such

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<PAGE>

discharge or release. If Cytokinetics or Cytokinetics Personnel release
Hazardous Materials in violation of Hazardous Materials Laws, Cytokinetics will
promptly take all actions at its sole cost and expense to the extent required by
Hazardous Materials Laws to either (i) cause any and all such Hazardous
Materials to be removed from the Licensed Premises and transported solely by
duly licensed haulers to duly licensed facilities for final disposal of such
materials and waste, except as discharged into the sanitary or storm sewer in
strict accordance and conformity with all applicable Hazardous Materials Laws or
(ii) handle, treat, use, store, deal with and manage any and all such Hazardous
Materials in, on, under or about the Licensed Premises in compliance with all
applicable Hazardous Materials Laws. Upon expiration or earlier termination of
this Agreement, to the extent required by Hazardous Materials Laws, Cytokinetics
will cause all Hazardous Materials placed on, under or about the Licensed
Premises by Cytokinetics Personnel to be removed and transported for use,
storage or disposal in accordance and compliance with all applicable Hazardous
Materials Laws.

            (c) Portola represents that it has obtained and will continue to
maintain all required governmental permits and licenses to perform all
activities anticipated to be performed pursuant to the Collaboration, including
to use, store, handle and dispose of Hazardous Materials as may be necessary to
perform such activities hereunder. Portola shall at all times perform all of its
obligations under this Agreement in full compliance with all Hazardous Materials
Laws, including applicable permits and licenses and shall maintain such permits
and licenses in place at all times throughout the Term. Portola shall be
responsible for posting any notices required pursuant to the California Safe
Drinking Water and Toxic Enforcement Act (Proposition 65).

            (d) To Portola's knowledge (without further duty of inquiry), (i) no
Hazardous Material is present on the Master Premises in violation of Hazardous
Materials Laws; and (ii) no action, proceeding or claim is pending or threatened
regarding the Master Premises concerning any Hazardous Material or pursuant to
any Hazardous Materials Law. Under no circumstance shall Cytokinetics be liable
for, and Portola shall indemnify, defend (with counsel approved by
Cytokinetics), protect and hold harmless Cytokinetics, its agents, contractors,
stockholders, directors, successors, representatives, and assigns from and
against, all losses, costs, claims, judgments, penalties, fines, liabilities and
damages (including attorneys' and consultants' fees) arising out of any
Hazardous Material present at any time on or about the Master Premises, or the
violation of any Hazardous Materials Laws by Portola Personnel, except to the
extent that any of the foregoing actually results from the release or emission
of Hazardous Material by Cytokinetics or its agents or employees (which shall in
no event be deemed to include Portola Personnel, or Portola's other agents,
employees or contractors) in violation of Hazardous Materials Laws.

      9. CONDITION OF LICENSED PREMISES AND PERSONAL PROPERTY.

            (a) CONDITION OF LICENSED PREMISES. Except as expressly set forth
herein, Cytokinetics accepts the Licensed Premises in its AS-IS condition with
all faults and without any representation or warranty of any kind or nature
whatsoever, or any obligation on the part of Portola to modify, improve or
otherwise prepare the Licensed Premises for Cytokinetics' occupancy. Upon
expiration or earlier termination of this Agreement, the Licensed Premises shall
be surrendered to Portola in the condition it was on the Effective Date,
reasonable wear and tear and damage caused by Portola or casualty or repairs not
Cytokinetics responsibility

                                      19.
<PAGE>

hereunder excepted. Notwithstanding the foregoing or the provisions of subpart
(b) below, Portola shall deliver possession of the Licensed Premises and the
Personal Property to Cytokinetics on the Effective Date in good, broom clean
condition, with all building systems serving the Licensed Premises in good
working order and in compliance with all laws including Hazardous Materials
Laws. Cytokinetics' acceptance of the Licensed Premises or the Personal Property
shall not be deemed a waiver of Cytokinetics' right to have defects in the
Licensed Premises or the Personal Property repaired at no cost to Cytokinetics.
Cytokinetics shall give notice to Portola whenever any such defect becomes
reasonably apparent, and Portola shall repair or cause the Landlord to repair
such defect as soon as practicable.

            (b) CONDITION OF PERSONAL PROPERTY. Except as expressly set forth
herein, Cytokinetics accepts the Personal Property in its AS-IS condition, and
Cytokinetics acknowledges and agrees that Portola has made no representation or
warranty of any kind, express or implied, with respect to the design, operation
or condition of the Personal Property or any part thereof, or its fitness for a
particular purpose. Cytokinetics shall take no action that causes any existing
warranty covering all or any portion of the Personal Property to be invalidated
(other than properly using the Personal Property as permitted under this
Agreement), and Cytokinetics agrees to use the Personal Property in a manner so
as not to damage the Personal Property throughout the Term hereof. Cytokinetics
expressly acknowledges and agrees that Portola shall have priority access to,
and use of the Personal Property, and Cytokinetics shall have access to the
Personal Property on an "as available" basis, provided that Portola shall use
reasonable efforts to accommodate Cytokinetics' need to use such Personal
Property and Cytokinetics shall have the right to use the Personal Property
currently located in the Exclusive Space or specifically designated for use by
Cytokinetics at all times and Cytokinetics shall have the right to use the
Personal Property located in the Lab Space as part of Cytokinetics' use of the
Lab Space as described in Section 3(b) above. Upon the expiration or earlier
termination of this Agreement, the Personal Property shall be surrendered to
Portola in its then, as-is condition, damage caused by Cytokinetics excepted.
The Personal Property shall remain the property of Portola, and Cytokinetics
shall have no right, title or interest therein except the right to use set forth
in Section 2(a).

            (c) Cytokinetics shall maintain the Exclusive Space in a neat and
orderly condition and shall not damage the Licensed Premises. Except as set
forth in the immediately preceding sentence, Portola shall be solely responsible
maintaining the Licensed Premises, the Personal Property, and the building
systems servicing the Licensed Premises, in good, clean condition and in
compliance with all laws, including making or causing the Landlord to make all
necessary repairs and replacements.

      10. USE/ALLOCATION OF LIABILITY. Cytokinetics shall be solely responsible
for any waste committed with respect to the Licensed Premises or the Master
Premises by Cytokinetics or its employees, agents, representatives or affiliates
(which shall in no event be deemed to include Portola Personnel or Portola's
other agents, employees or contractors). Cytokinetics shall not violate any
provision of the Sublease but shall have no responsibility for the obligations
of Portola as the tenant thereunder.

      11. INSURANCE AND LIABILITY. During the term of this Agreement, each Party
shall, at its own cost and expense, carry commercial general liability insurance
with a single combined

                                      20.
<PAGE>

liability and property damage limit of at least $[***]. Such insurance shall
have customary coverages with exclusions reasonably approved by the other Party
to protect the other Party against liability for injury or death to persons and
loss or damage to property arising out of or in connection with the use of the
license herein granted. Within three (3) days of the Effective Date, each Party
shall furnish to the other certificates from its insurance carrier certifying
that the above-specified insurance has been fully paid for and is in full force
and effect. The amount of such insurance shall not limit the liability of either
Party to the other under Article 12 hereof. All liability policies that
Cytokinetics is required to be obtained hereunder will show Portola, Millennium
and Landlord (as defined in the Master Lease) as additional insureds. All
liability policies that Portola is required to be obtained hereunder will show
Cytokinetics as an additional insured. All policies shall contain a provision
that such policies will not be cancelled or reduced without at least thirty (30)
days prior written notice to the other Party. Notwithstanding anything to the
contrary herein, the Parties hereto release each other and their respective
agents, employees, successors and assignees from all liability for injury to any
person or damage to any property that is caused by or results from a risk which
is actually insured against or which would normally be covered by all risk
property insurance, without regard to the negligence or willful misconduct of
the entity so released. Each of Portola and Cytokinetics shall promptly inform
its insurance carrier of the foregoing release and waiver of subrogation and
obtain all required certificates or waivers from such insurance carriers. All of
Portola's and Cytokinetics' repair and indemnity obligations under this
Agreement shall be subject to the release and waiver contained in this
paragraph.

      12. INDEMNITY.

            (a) Cytokinetics agrees to defend (with counsel approved by
Portola), indemnify and hold Portola harmless from and against any and all
third-party claims, mechanics liens, damages, expenses (including, without
limitation, attorneys' fees and charges), suits, losses, liabilities for any
death, injury, damage or loss caused by or arising from (i) any negligence or
willful acts of Cytokinetics or its agents, officers, representatives or
employees; (ii) any breach by Cytokinetics or its agents, officers,
representatives or employees of any of its obligations under this Agreement;
(iii) any discharge or release of Hazardous Materials by Cytokinetics or its
agents, officers, representatives or employees in violation of Hazardous
Materials Laws as described under Section 8(b); provided, however, that nothing
in this provision shall render Cytokinetics liable or responsible for any loss
or damage to property or for injury, including death, to persons to the extent
caused by or arising out of the negligent or willful acts or omissions, breach
of this Agreement or violation of laws or permits (including Hazardous Materials
Laws) of Portola, Portola Personnel, or Portola agents, officers,
representatives or employees.

            (b) Portola agrees to defend (with counsel approved by
Cytokinetics), indemnify and hold Cytokinetics harmless from and against any and
all third-party claims, mechanics liens, damages, expenses (including, without
limitation, attorneys' fees and charges), suits, losses, liabilities for any
death, injury, damage or loss caused by, arising from or connected with (i) any
negligence or willful acts of Portola or its agents, officers, representatives
or employees; (ii) any breach by Portola or its agents, officers,
representatives or employees of any of its obligations under this Agreement;
(iii) any discharge or release of Hazardous Materials by Portola or its agents,
officers, representatives or employees or Portola Personnel, including any

***   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.

                                      21.
<PAGE>

release or discharge occurring in the course of Portola or its agents, officers,
representatives or employees carrying out its obligations under this Agreement;
(iv) Portola's or its agent's, officer's, representative's or employee's or the
Portola Personnel's use of the Master Premises; or (v) the exercise of any
rights hereunder by Portola or its agents, officers, representatives or
employees or any Portola Personnel or visitors; provided, however, that nothing
in this provision shall render Portola liable or responsible for any loss or
damage to property or for injury, including death, to persons caused solely by
or arising solely out of the negligent or willful acts or omissions of
Cytokinetics, its agents, officers, representatives or employees (which shall in
no event be deemed to include Portola Personnel or Portola's other agents,
employees or contractors).

      13. TERM; EXTENSION.

            (a) TERM. The term of this Agreement shall begin on the Effective
Date and, subject to Section 13(b), end on [***] (the "TERM").

            (b) EXTENSION. The Parties may extend the Term for one (1)
additional year by mutual written agreement not more than [***] ([***]) days
before the end of the Term. If either Party notifies the other Party of its
interest in extending the Term, both Parties shall negotiate in good faith and
use commercially reasonable efforts to reach an agreement on such extension
acceptable to each Party during the last [***] ([***]) days of the Term. The
extension granted herein is conditioned on Cytokinetics not being in default of
this Agreement beyond any applicable cure period at the effective date of such
extension.

      14. TERMINATION.

            (a) CASUALTY. If the Master Premises, or any material portion
thereof, are damaged or destroyed, Portola may terminate this Agreement by
delivering written notice to Cytokinetics of such termination. Such termination
shall be effective immediately upon delivery of such notice. If the Licensed
Premises, or any material portion thereof, are damaged or destroyed,
Cytokinetics may terminate this Agreement by delivering written notice to
Portola of such termination. Such termination shall be effective immediately
upon delivery of such notice.

            (b) CONDEMNATION. If any portion of the Master Premises is taken or
condemned for any public purpose, this Agreement shall terminate as of the
effective date of the condemnation or taking. All proceeds from any taking or
condemnation referred to in this paragraph shall be the sole property of
Portola, and Cytokinetics shall have no right or interest to any portion
thereof.

            (c) UNCURED MATERIAL BREACH. In addition to any other remedies that
may be available to the non-breaching Party at law or equity, if a Party
materially breaches this Agreement, and the breaching Party has not cured such
breach within [***] ([***]) days of written notice of such material breach from
the non-breaching Party, then the non-breaching Party may terminate this
Agreement by delivering a second written notice promptly after expiration of
such [***] ([***]) day period. In the event of Cytokinetics' uncured material
breach, at the end of such [***] ([***]) day period, Portola shall have the
immediate right of re-entry and may remove all persons and property from the
Licensed Premises.

***   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.

                                      22.
<PAGE>

            (d) TERMINATION RIGHT. This Agreement may be terminated by either
Party after [***], without cause, upon [***] ([***]) days written
notice to the other Party.

            (e) TERMINATION OF SUBLEASE. This Agreement shall terminate
immediately upon a termination of the Sublease.

            (f) EFFECTS OF EXPIRATION OR TERMINATION.

                  (i) NO PREJUDICE. The termination or expiration of the
Agreement for any reason shall be without prejudice to any rights which shall
have accrued to the benefit of either Party prior to such termination or
expiration, including any damages arising from any breach hereunder. Such
termination or expiration shall not relieve either Party from obligations which
are expressly indicated to survive termination or expiration of the Agreement.

                  (ii) SURRENDER OF LICENSED PREMISES. Upon expiration or
earlier termination of this Agreement, Cytokinetics shall surrender the Licensed
Premises to Portola in its then, as-is condition (damage by Cytokinetics
excepted), and Cytokinetics shall, at its sole cost and expense, remove or cause
to be removed all of Cytokinetics' equipment and other installations from the
Licensed Premises and repair any damage to the Master Premises caused by such
removal. Upon the termination of this Agreement, Cytokinetics shall have no
further right to use the Licensed Premises. Upon request by Portola,
Cytokinetics shall execute, acknowledge and deliver to Portola an instrument in
writing sufficient in Portola's judgment to evidence the expiration or
termination of this Agreement and to disclaim any further right of Cytokinetics
under this Agreement.

                  (iii) SURVIVAL. The terms and provisions of the following
Articles and Sections shall survive any expiration or termination of this
Agreement: Articles 1, 4, 5, 7, 12 and 15; and Sections 6(b)-6(g), 8(b) (solely
with respect to claims arising during the Term), 9(b), 13(b) and 14(f).

      15. GENERAL.

            (a) CORPORATE AUTHORITY.

                  (i) Cytokinetics represents and warrants to Portola that
Cytokinetics is validly formed and duly authorized and existing, that
Cytokinetics is qualified to do business in California, that Cytokinetics has
the full right and legal authority to enter into this Agreement and is
authorized to execute and deliver this Agreement in accordance with its terms.

                  (ii) Portola represents and warrants to Cytokinetics that
Portola is validly formed and duly authorized and existing, that Portola is
qualified to do business in California, that Portola has the full right and
legal authority to enter into this Agreement is authorized to execute and
deliver this Agreement in accordance with its terms.

            (b) NOTICES. Any notice or other communication required or permitted
to be delivered to any Party must be in writing and shall be deemed properly
delivered, given and

***   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.

                                      23.
<PAGE>

received either when delivered by hand, or two (2) business days after being
sent by: (i) registered mail; (ii) courier or express delivery service; or (iii)
by facsimile; in each case to the address or facsimile telephone number set
forth beneath the name of such Party below (or to such other address or
facsimile telephone number as such Party shall have specified in a written
notice given to the other Party):

                  if to Portola:

                       Portola Pharmaceuticals, Inc.
                       270 East Grand Avenue. Suite 22
                       South San Francisco, CA  94080
                       Attention:  Matt Birrell
                       Telephone: 650-246-7424
                       Facsimile: 650-246-7776

                  if to Cytokinetics:

                       Cytokinetics, Inc.
                       280 East Grand Avenue
                       South San Francisco, CA  94080
                       Attention:  Robert Blum
                       Executive Vice President,
                       Finance and Corporate Development
                       Chief Financial Officer
                       Telephone: 650-624-3000
                       Facsimile: 650-624-3010

            (c) GOVERNING LAW. This Agreement shall be construed in accordance
with, and governed in all respects by, the laws of the State of California
(without giving effect to principles of conflicts of laws that would require the
application of any other law).

            (d) TIME. Time is of the essence with respect to the performance of
each and every provision of this Agreement in which time of performance is a
factor. All references to days or months contained in this Agreement shall be
deemed to mean calendar days or calendar months unless otherwise specifically
stated.

            (e) ASSIGNMENT. This Agreement may not be assigned by either party
without the prior written consent of the other party, such consent not to be
unreasonably withheld, except that either party may assign this Agreement,
without such consent, (i) to an Affiliate, or (ii) to a successor in connection
with a merger or a sale of all or substantially all of the assets to which this
Agreement pertains. Any such assignment by a party in violation of the foregoing
shall be null and void.

            (f) SEVERABILITY. If any provision of this Agreement, or the
application of any such provision to any Party or set of circumstances, is
determined to be invalid, unlawful, void or unenforceable to any extent, the
remainder of this Agreement, and the application of such provision to a Party or
circumstances other than those as to which it is determined to be invalid,

                                      24.
<PAGE>

unlawful, void or unenforceable, shall not be impaired or otherwise affected and
shall continue to be valid and enforceable to the fullest extent permitted by
law.

            (g) WAIVER. No failure on the part of any Party to exercise any
power, right, privilege or remedy under this Agreement, and no delay on the part
of any Party in exercising any power, right, privilege, or remedy under this
Agreement, shall operate as a waiver of such power, right, privilege, or remedy;
and no single or partial exercise of any such power, right, privilege, or remedy
shall preclude any other or further exercise thereof or of any other power,
right, privilege, or remedy. No Party shall be deemed to have waived any claim
arising out of this Agreement, or any power, right, privilege, or remedy under
this Agreement, unless the waiver of such claim, power, right, privilege, or
remedy is expressly set forth in a written instrument duly executed and
delivered on behalf of such Party; and any such waiver shall not be applicable
or have any effect except in the specific instance in which it is given.

            (h) BROKERS. Cytokinetics and Portola each represent to the other
Party that they have not had any contract or dealings with or communications in
connection with this transaction, through any real estate broker or other person
who can claim a right to a commission or finder's fee as a procuring cause of
the transaction contemplated herein. In the event that any broker or other
person makes a claim based upon any contract, dealings or communication, the
Party through whom the broker or finder makes its claim agrees to defend, hold
harmless and indemnify the other from and against such claim, and all
liabilities, costs and expenses arising therefrom.

            (i) ENTIRE AGREEMENT; AMENDMENTS. This Agreement contains the entire
agreement of Portola and Cytokinetics with respect to the Licensed Premises and
the Collaboration, and there are no oral agreements between Portola and
Cytokinetics with respect thereto. Notwithstanding the foregoing or anything to
the contrary herein, the Consulting Agreement shall govern any Services (as
defined in the Consulting Agreement) provided to Cytokinetics by Charles Homcy.
This Agreement supersedes and cancels any and all previous negotiations,
arrangements, brochures, agreements, and understandings, if any, between Portola
and Cytokinetics with respect to the Collaboration or the Licensed Premises. No
amendments, modifications or changes herein or hereof shall be binding upon any
Party hereto unless set forth in a document duly executed by all Parties hereto.

            (j) COUNTERPARTS. This Agreement may be executed in multiple
counterparts, each of which shall be deemed an original and with the same effect
as if all Parties hereto had signed the same document. All of such counterparts
shall be construed together and shall constitute one instrument, but in making
proof, it shall be only necessary to produce a single such counterpart.

            (k) RECITALS. Each and every recital is incorporated into this
Agreement as if fully set forth herein.

            (l) RELATIONSHIP OF THE PARTIES. Each Party shall be deemed to be an
independent contractor and not an agent, joint venturer, or representative of
the other Party. No Party may create any obligations or responsibilities on
behalf of or in the name of the other

                                      25.
<PAGE>

Party. No Party shall hold itself out to be a partner, employee,
franchisee, representative, servant, or agent of the other Party.

            (m) CONSTRUCTION.

                  (i) For purposes of this Agreement, whenever the context
requires: (A) the singular number shall include the plural, and vice versa; (B)
the masculine gender shall include the feminine and neuter genders; (C) the
feminine gender shall include the masculine and neuter genders; and (D) the
neuter gender shall include the masculine and feminine genders.

                  (ii) The Parties hereto agree that any rule of construction to
the effect that ambiguities are to be resolved against the drafting Party shall
not be applied in the construction or interpretation of this Agreement.

                  (iii) As used in this Agreement, the words "include" and
"including," and variations thereof, shall not be deemed terms of limitation,
but rather shall be deemed to be followed by the words "without limitation."

                  (iv) Except as otherwise indicated, all references in this
Agreement to "Sections" and "Schedules" are intended to refer to Sections of
this Agreement and Schedules to this Agreement.

                            [SIGNATURE PAGE FOLLOWS]

                                      26.
<PAGE>

         IN WITNESS WHEREOF, the Parties have caused this agreement to be duly
executed and delivered as of the Effective Date.

                                      PORTOLA PHARMACEUTICALS, INC.
                                      a Delaware corporation

                                      By: /s/ Charles Homey
                                         ---------------------------------------
                                      Print Name: Charles Homey
                                           -------------------------------------
                                      Its: President & CEO
                                          --------------------------------------

                                      Date: 8/19/04
                                           -------------------------------------

                                      CYTOKINETICS, INC.
                                      a Delaware corporation

                                      By: /s/ Robert I. Blum
                                         ---------------------------------------
                                      Print Name: Robert I. Blum
                                           -------------------------------------
                                      Its: EVP Corp. Dev. & CFO
                                          --------------------------------------

                                      Date: 8/19/04
                                           -------------------------------------

                                      27.
<PAGE>

                                   EXHIBIT A

                                    SUBLEASE

      THIS SUBLEASE ("Sublease"), dated November 7, 2003 for reference purposes
only, is entered into by and between MILLENNIUM PHARMACEUTICALS, INC. a Delaware
corporation ("Sublandlord"), and PORTOLA PHARMACEUTICALS, INC., a Delaware
corporation ("Subtenant").

                                    RECITALS

      A. Sublandlord, as successor in interest to COR Therapeutics, Inc. leases
certain premises (the "Premises") consisting of approximately 136,242 rentable
square feet in four buildings in South San Francisco, California more
particularly described as (i) the one-story building commonly known as 256 East
Grand Avenue, (ii) the two-story building commonly know as 260 East Grand
Avenue, (iii) Suites 20, 26, 35, 45, 50 and 70 in the one-story building
commonly known as 250 East Grand Avenue, and (iv) the westerly portion of the
two-story building commonly known as 270 East Grand Avenue, pursuant to a
certain Lease, dated as of July 1, 2001 between BRITANNIA POINTE GRAND LIMITED
PARTNERSHIP, as landlord (the "Master Landlord"), and Sublandlord's predecessor
in interest, COR Therapeutics, Inc., as tenant, (the "Master Lease"), a copy of
which is attached hereto as EXHIBIT A. Capitalized terms herein not otherwise
defined herein shall have the same meanings as provided in the Master Lease.

      B. Sublandlord desires to sublease to Subtenant, and Subtenant desires to
sublease from Sublandlord a portion of the Premises consisting of approximately
26,916 square located in the westerly portion of the two-story building commonly
known as the westerly portion of 270 East Grand Avenue and more particularly
shown on the layout attached at EXHIBIT B hereto ("Sublease Premises") upon the
terms and conditions provided for herein.

      NOW, THEREFORE, in consideration of the mutual covenants and conditions
contained herein, Sublandlord and Subtenant covenant and agree as follows:

                                    AGREEMENT

      1.    SUBLEASE PREMISES. Sublandlord hereby leases to Subtenant, and
Subtenant hereby leases from Sublandlord, the Sublease Premises, upon and
subject to the terms and conditions set forth herein, together with the
non-exclusive use of 3 parking spaces per 1,000 rentable square feet in the
Sublease Premises.

      2.    TERM. The term of this Lease shall commence on the date of
termination of the Transition Services Agreement between Sublandlord and
Subtenant being executed contemporaneously, subject to satisfaction of the
Conditions Precedent (defined below) (the "Commencement Date"). The term of this
Sublease shall end on June 30, 2009 unless sooner terminated or extended in
accordance with the provisions hereof.

      3.    [INTENTIONALLY OMITTED]

                                       1

<PAGE>

      4.    CONDITIONS PRECEDENT. The conditions listed in this paragraph
("Conditions Precedent") must be satisfied or waived by Subtenant prior to
commencement of the Sublease term. The parties anticipate that the Conditions
Precedent will be satisfied on or before July 1, 2004, and each covenants to use
its best efforts to effect their satisfaction by such time.

            (a) The parties shall have entered into the Transition Services
Agreement between Sublandlord and Subtenant being executed contemporaneously
herewith (the "TSA");

            (b) Those services and utilities to be installed by Sublandlord
necessary for the Sublease Premises to be operated as a stand-alone facility
have been installed or configured, in accordance with the TSA;

            (c) All of the Equipment (as that term is defined in the TSA) has
been transferred to the Sublease Premises in accordance with the TSA;

            (d) Sublandlord shall have completed all site closure activities
relative to the Sublease Premises and shall have received all necessary
governmental or regulatory approvals as may be required to decommission the
Sublease Premises and obtain site closure of all permits and licenses relating
to Sublandlord's use of Hazardous Materials in the Sublease Premises, in
accordance with the TSA;

            (e) Sublandlord shall have vacated the Subleased Premises and shall
have delivered possession of the Subleased Premises to Subtenant; and

            (f) Master Landlord shall have consented to this Sublease.

      5.    USE. Subtenant shall be permitted to use the Sublease Premises
consistent with the permitted uses under the Master Lease.

      6.    RENT.

            (a) BASE RENT.

                  (i) Starting on the Commencement Date, Subtenant shall pay as
base rent ("Base Rent") for the Sublease Premises in advance, on or before the
first day of each month, without deduction or offset, monthly rent in the
amounts set forth below. Base Rent and Additional Rent (defined below) shall be
payable to Sublandlord at the address stated herein for Sublandlord. Base Rent
and Additional Rent shall collectively be referred to herein as "Rent." Rent for
any period during the term hereof which is for less than one month shall be a
pro rata portion of the monthly installment based on the number of days in the
month at issue.

<TABLE>
<CAPTION>
         PERIOD                                       MONTHLY RENT
<S>                                             <C>
Commencement Date - 12/04                       $[***] ($[***]/sq.ft.)
      1/05 - 12/05                              $[***] ($[***]/sq.ft.)
      1/06 - 6/30/07                            $[***] ($[***]/sq.ft.)
    7/1/07 - 6/30/09                            Fair Market Rental
</TABLE>

*** 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.

                                       2.

<PAGE>

                  (ii) "Fair Market Rental," as that term is used in this
subsection shall mean the current market rate per month being charged to new
tenants for triple net leases of comparable office, laboratory space and [***]
facility in the South San Francisco area, determined as follows:

                        (1) At least 60 but not more than 90 days prior to June
30, 2007, Sublandlord shall give Subtenant written notice of its estimate of
Fair Market Rental. Subtenant shall have fifteen (15) days after receipt of
Sublandlord's notice to accept such value or to object thereto in writing. In
the event Subtenant objects, Sublandlord and Subtenant shall attempt to agree
upon the Fair Market Rental, using their best good faith efforts. If Sublandlord
and Subtenant fail to reach agreement within such fifteen (15) days, then each
party's determination shall be submitted to arbitration in accordance with the
procedure set forth in the following subsections.

                        (2) Sublandlord and Subtenant shall each appoint one
arbitrator who shall by profession be a real estate broker who shall have been
active over the five (5) year period immediately preceding the date of such
appointment in the leasing of office and laboratory space in the South San
Francisco area.

                        (3) Not later than ten (10) days after both arbitrators
are appointed, each party shall separately but simultaneously submit in a sealed
envelope to each arbitrator their separate suggested Fair Market Rental values.
If the higher rate of the two submitted suggested Fair Market Rental values does
not exceed the lower rate by more than five percent (5%), then the two rates
shall be averaged (thus splitting the difference and avoiding additional
arbitration costs), with the resulting value becoming the Fair Market Rental.

                        (4) If the Fair Market Rental is not established by the
provisions in subsection (3) above, the two arbitrators appointed shall, on of
before fifteen (15) days from the date of the appointment of the last appointed
arbitrator, agree upon and appoint a third arbitrator who shall be qualified
under the same criteria set forth above for qualification of the initial two
arbitrators.

                        (5) Each of the three arbitrators, within thirty (30)
days of the appointment of the third arbitrator, shall independently determine
the Fair Market Rental. If the higher and lower values determined by the
arbitrators so not differ by more five percent (5%) from the middle value, all
values shall be averaged and the resulting value shall be determined to be the
Fair Market Rental. If either of the arbitrator's values differ from the middle
value by more than five percent (5%), such value shall not be considered and the
remaining values shall be averaged to determine the Fair Market Rental. If two
of the arbitrators' values differ from the middle value by more than five
percent (5%), neither such value shall be considered, and the middle value shall
be deemed to be the Fair Market Rental.

                        (6) The cost of arbitration shall be paid by Sublandlord
and Subtenant equally.

*** 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.

                                       3.

<PAGE>

            (b) ADDITIONAL RENT. Subtenant shall pay to Sublandlord, as
additional rent ("Additional Rent"), Subtenant's Pro Rata Share of Operating
Expenses accruing during the term of this Sublease. Notwithstanding the
foregoing, in the event any amounts payable by Sublandlord to Master Landlord
are (i) due to Sublandlord's breach of any provision of the Master Lease, (ii)
due to Sublandlord's negligence or willful misconduct, or (iii) are for the sole
benefit of Sublandlord, such amounts shall not be pro rated between Sublandlord
and Subtenant and shall be the sole responsibility of Sublandlord. For purposes
hereof, Subtenant's Pro Rata Share means 25.36%.

            (c) PERSONAL PROPERTY TAXES. Subtenant shall be responsible for and
shall pay prior to delinquency all taxes and assessments levied against or by
reason of (a) any and all alterations, additions and items installed or placed
on or in the Sublease Premises and taxed as personal property rather than as
real property, and/or (b) all personal property, trade fixtures and other
property placed by Subtenant on or about the Sublease Premises

      7.    AS-IS. The Sublease Premises and all improvements will be taken over
on an "as is" basis.

      8.    INCORPORATION OF MASTER LEASE.

            (a) Except as otherwise provided in this Sublease, all of the terms
and provisions of the Master Lease are incorporated into and made a part of this
Sublease, and the rights and obligations of the parties under the Master Lease
are hereby imposed upon the parties hereto with respect to the Sublease
Premises, the Sublandlord being substituted for the Landlord in the Master
Lease, the Subtenant being substituted for the Tenant in the Master Lease and
the Sublease Premises being substituted for the Premises in the Master Lease;
provided, however, that the term "Landlord" in the following sections of the
Master Lease shall mean (i) Master Landlord, not Sublandlord: Section 1.2, 9.2
(first full paragraph), 9.2(a), 12.1(d), 17.1, 17.4 and 17.5 and (ii) both
Master Landlord and Sublandlord: Sections 9.2(b), 9.2(c), 9.2(e), 9.3.
Notwithstanding the foregoing, the following Sections of the Master Lease are
not incorporated herein: Sections 1.1 (a), 1.3, 2.1, 2.3, 2.6, 3.1, 7 (except
for the definitions necessary for Section 5(b) above), 9.2(d), 10.2(c), 19.1 and
19.15.

            (b) In the event of any conflict between this Sublease and the
Master Lease, as between Sublandlord and Subtenant, the terms and conditions of
this Sublease shall control. Further, if Rent is abated under the Master Lease,
Rent hereunder shall also be abated in the same proportion.

      9.    INDEMNITY AND REPRESENTATIONS. The following provisions and
obligations shall survive the termination of this Sublease:

            (a) Subtenant shall indemnify, defend, protect, and hold Sublandlord
harmless from and against all actions, claims, demands, costs, liabilities,
losses, reasonable attorneys' fees, damages, penalties, and expenses
(collectively "Claims") which may be brought or made against Sublandlord or
which Sublandlord may pay or incur to the extent caused by (i) a breach of this
Sublease by Subtenant, (ii) any violation of law by Subtenant or its employees,
agents, contractors or invitees ("Agents") relating to the use or occupancy of
the Sublease Premises, (iii) the negligence or willful misconduct of Subtenant
or its Agents, or (iv) the storage, use, release

                                       4.

<PAGE>

or disposal of Hazardous Materials (as defined below) on or about the Premises
by Subtenant or Subtenant's employees, contractors, agents or licensees.
Notwithstanding anything to the contrary in this Sublease or Master Lease,
Subtenant shall have no obligation to clean up or to comply with any law
regarding, or to reimburse, indemnify, defend or hold harmless Sublandlord or
Master Landlord with respect to, any Hazardous Materials discovered on the
Sublease Premises which existed prior to the Commencement Date of this Sublease.

            (b) Sublandlord shall indemnify, defend, protect, and hold Subtenant
harmless from and against all actions, claims, demands, costs, liabilities,
losses, reasonable attorneys' fees, damages, penalties and expenses which may be
brought or made against Subtenant or which Subtenant may pay or incur to the
extent caused by (i) the negligence or willful misconduct of Sublandlord or its
Agents occurring on or about the Premises or Sublease Premises; (ii) the failure
by Sublandlord to comply with or perform its obligations under the Master Lease
and/or this Sublease, (iii) a breach by Sublandlord of any of its
representations or warranties to Subtenant under this Sublease, or (iv) storage,
use, release or disposal of Hazardous Materials on or about the Sublease
Premises or Premises by Sublandlord or Sublandlord's employees, contractors,
agents or licensees. As used herein, "Hazardous Materials" means any substance
or material which is classified or considered to be hazardous or toxic under any
present or future federal, state, regional or local law relating to the use,
storage, treatment, existence, release, emission, discharge, generation,
manufacture, disposal or transportation of any such substances.

            (c) Sublandlord represents to Subtenant that (A) the Master Lease is
in full force and effect, (B) the copy of the Master Lease which is attached to
this Sublease as EXHIBIT A is a true, correct and complete copy of the Master
Lease, (C) to Sublandlord's best knowledge, no Event of Default exists on the
part of Sublandlord under the Master Lease, (D) to Sublandlord's best knowledge,
there are no pending or threatened actions, suits or proceedings before any
court or administrative agency against Sublandlord which could, in the
aggregate, adversely affect the Sublease Premises or of Sublandlord to perform
its obligations under the Sublease, and Sublandlord is not aware of any facts
which might result in any actions, suits or proceedings, and (E) to
Sublandlord's best knowledge (x) Sublandlord has not discharged, disposed of or
released any Hazardous Materials in or about the Sublease Premises or Premises
except in compliance with applicable laws and no action, proceeding, or claim is
pending, or threatened concerning any Hazardous Materials arising in connection
with Sublandlord's use of the Sublease Premises or Premises, and (y) Sublandlord
has not transported, stored, used, manufactured, emitted, disposed of or
released, or exposed to its employees or others to, Hazardous Materials on or
about the Sublease Premises or Premises in violation of any law, rule,
regulation, treaty or statute promulgated by any governmental authority or any
permit held by Sublandlord. Subtenant expressly acknowledges that the foregoing
representations under this clause (c) are made with respect to the period from
and after February 12, 2002.

      10.   BROKERAGE. Each party warrants and represents to the other that such
party has not retained any other real estate broker, finder or any other person
whose services would form the basis for any claim for any commission or fee in
connection with this Sublease or the transactions contemplated hereby. Each
party agrees to save, defend, indemnify and hold the other party free and
harmless from any breach of its warranty and representation as set forth in the
preceding sentence, including the other party's attorneys' fees.

                                       5.

<PAGE>

      11.   SUBLANDLORD'S OBLIGATIONS. Sublandlord shall have no obligation to
Subtenant with respect to the Sublease Premises during the term hereof except as
expressly otherwise provided herein nor shall Sublandlord have any obligation to
Subtenant with respect to the performance by Master Landlord of any obligations
of Master Landlord under the Master Lease, except to use best efforts to enforce
Master Landlord's obligations under the Master Lease. Such enforcement shall
include, without limitation, upon Subtenant's request, (a) immediately notifying
Master Landlord of its non-performance under the Master Lease and requesting
that Master Landlord perform its obligations under the Master Lease and/or (b)
assigning Sublandlord's rights under the Master Lease to Subtenant to the extent
necessary to permit Subtenant to institute legal proceedings against Master
Landlord to obtain the performance of Master Landlord's obligations under the
Master Lease; provided, however, that if Subtenant commences a lawsuit or other
action, Subtenant shall pay all costs and expenses incurred in connection
therewith, and Subtenant shall indemnify Sublandlord against, and hold
Sublandlord harmless from, all costs and expenses incurred by Sublandlord in
connection therewith.

      12.   EARLY TERMINATION OF MASTER LEASE. If, without the fault of
Sublandlord hereunder the Master Lease should terminate prior to the expiration
of this Sublease, Sublandlord shall have no liability to Subtenant. To the
extent that the Master Lease grants Sublandlord any discretionary right to
terminate the Master Lease, whether due to casualty, condemnation, or otherwise,
Sublandlord shall have the right to exercise such right with regard to the
Sublease Premises in its sole and absolute discretion.

      13.   MODIFICATIONS TO MASTER LEASE. Sublandlord shall not amend or modify
the Master Lease in such a manner as to adversely affect Subtenant's use of the
Sublease Premises or increase the obligations or decrease the rights of
Subtenant hereunder, without the prior written consent of Subtenant, which may
be granted or withheld at Subtenant's sole discretion.

      14.   QUIET ENJOYMENT. Subtenant shall peacefully have, hold and enjoy the
Sublease Premises, subject to the terms and conditions of this Sublease and
subject to the Master Lease, provided that Subtenant pays all rent and performs
all of Subtenant's covenants and agreements contained herein. If Master Landlord
seeks to terminate the Master Lease because of a default or alleged default by
Sublandlord under the Master Lease (other than a default or alleged default
caused by the default by Subtenant under this Sublease), Sublandlord shall take
all action required to reinstate the Master Lease. In the event that Sublandlord
defaults in the performance or observance of any of Sublandlord's obligations
under this Sublease or receives a notice of default from Master Landlord under
the Master Lease, then Subtenant shall give written notice to Sublandlord
specifying in what manner Sublandlord has defaulted. If such default shall not
be cured within a reasonable time, but in no event later than thirty (30) days
after Sublandlord's receipt of such written notice from Subtenant (except that
if such default cannot be cured within said thirty (30) day period, this period
shall be extended for an additional reasonable time, provided that Sublandlord
commences to cure such default within such thirty (30) day period and proceeds
diligently thereafter to effect such cure as quickly as possible), then
Subtenant shall be entitled, at Subtenant's option, to cure such default and
promptly collect from Sublandlord Subtenant's reasonable expenses in so doing
(including, without limitation, reasonable attorneys' fees and court costs)
unless such default by Sublandlord is caused by a default of Subtenant hereunder
(in which case Sublandlord shall not be liable for Subtenant's costs to cure the
default). Subtenant shall not be required to wait the entire cure period
provided for herein if

                                       6.
<PAGE>

earlier action is required to prevent a termination by Master Landlord of the
Master Lease and Sublandlord has failed to take such earlier action. Nothing
contained herein shall entitle Subtenant to act on behalf of Sublandlord or in
Sublandlord's name.

      15.   CONSENT OF MASTER LANDLORD. If Subtenant desires to take any action
which requires the consent of Master Landlord pursuant to the terms of the
Master Lease, including, without limitation, the making of any alterations,
then, notwithstanding anything to the contrary herein, (a) Sublandlord,
independently, shall have the same rights of approval or disapproval as Master
Landlord has under the Master Lease, (b) Subtenant shall not take any such
action until it obtains the consent of both Sublandlord and Master Landlord, and
(c) Subtenant shall request that Sublandlord obtain Master Landlord's consent on
Subtenant's behalf and Sublandlord shall use commercially reasonable efforts to
obtain such consent and any out-of-pocket expense of obtaining such consent
shall be borne by Subtenant, unless Sublandlord and Master Landlord agree that
Subtenant may contact Master Landlord directly with respect to the specific
action for which Master Landlord's consent is required.

      16.   NO THIRD PARTY RIGHTS. The benefit of the provisions of this
Sublease is expressly limited to Sublandlord and Subtenant and their permitted
successors and assigns. Under no circumstances will any third party be construed
to have any rights as a third party beneficiary with respect to any of said
provisions.

      17.   MASTER LANDLORD CONSENT TO SUBLEASE. This Sublease and Sublandlord's
and Subtenant's obligations hereunder are conditioned upon having obtained the
written consent of the Master Landlord to this Sublease.

      18.   SURRENDER. Subtenant's obligation to surrender the Sublease Premises
shall be fulfilled if Subtenant (i) surrenders possession of the Sublease
Premises in the condition existing immediately prior to the Commencement Date,
ordinary wear and tear, Hazardous Materials existing immediately prior to the
Commencement Date, and interior improvements made by Subtenant which Sublandlord
states in writing may be surrendered at the termination of the Sublease
excepted; and (ii) completes all site closure activities relative to the
Sublease Premises and receives all necessary governmental or regulatory
approvals as may be required to decommission the Sublease Premises and obtain
the site closure of all permits and licenses relating to Subtenant's use of
Hazardous Materials in the Sublease Premises.

      19.   MUTUAL WAIVER OF SUBROGATION. The waiver of subrogation provision
set forth in Section 12.4 of the Master Lease shall be deemed a three party
agreement binding among and inuring to the benefit of Sublandlord, Subtenant and
Master Landlord (by reason of its consent to hereto).

      20.   NON-DISTURBANCE. In the event that the Sublease terminates prior to
the expiration of the term thereof for any reason other than as a result of an
event of default by Subtenant under the Sublease, the Sublease shall continue in
full force and effect, at Subtenant's option, as a direct lease between the
Master Landlord and Subtenant upon all of the terms, covenants and conditions of
the Sublease and Master Landlord shall recognize Subtenant's right to possession
of the Premises as provided for in the Sublease and shall not disturb
Subtenant's right to possession so long as an event of default does not exist in
the performance of Subtenant's obligations under the Sublease.

                                       7.

<PAGE>

      21.   COUNTERPARTS. This Sublease may be executed in any number of
counterparts, each of which counterparts shall be deemed to be an original, and
all of which together shall constitute one and the same instrument.

                   [balance of page left intentionally blank]

                                       8.

<PAGE>

      IN WITNESS WHEREOF, the parties have executed this Sublease as of the date
first written above.

ADDRESS:                             SUBLANDLORD

Millennium Pharmaceuticals, Inc.     MILLENNIUM PHARMACEUTICALS, INC.
75 Sidney Street                       a Delaware corporation
Cambridge, MA 02139

Attn: General Counsel                          /s/ Mark J. Levin
                                               --------------------------------
                                        By:    Mark J. Levin
                                        Title: Chairperson, President and Chief
                                               Executive Officer

                                     SUBTENANT

Portola Pharmaceuticals, Inc.        PORTOLA PHARMACEUTICALS, INC.,
270 East Grand Avenue                 a Delaware corporation
South San Francisco, CA 94080

Attn: ____________________________   By: /s/ [ILLEGIBLE]
                                         --------------------------------------
                                     Title: President & Chief Executive Officer

                                       9.
<PAGE>

                           CONSENT OF MASTER LANDLORD

      Notwithstanding any provision in the Master Lease prohibiting the sublease
of the Premises, the undersigned, as owner and holder of all right, [ILLEGIBLE]
and interest of Master Landlord under the Master Lease, hereby consents to the
foregoing sublease of the Premises and waives any objection to the sublease
contained herein and agrees to the provisions of Section 19 ("Nondisturbance")
contained therein.

                                      BRITANNIA POINTE GRAND LIMITED
                                      PARTNERSHIP, a Delaware limited
                                      partnership

                                      By:  Britannia Pointe Grand, LLC, a
                                      California limited liability company,
                                      General Partner

Dated: _____________________,         By: /s/ [ILLEGIBLE]
                                          ------------------------------------
                                      Title: MANAGER

                                       10.

<PAGE>
                                   EXHIBIT A

                     [COPY OF MASTER LEASE TO BE ATTACHED]

                                      11.
<PAGE>

                                      LEASE

Landlord:                 Britannia Pointe Grand Limited Partnership

Tenant:                   COR Therapeutics, Inc.

Date:                     July 1, 2001

                                TABLE OF CONTENTS

<TABLE>
<S>                                                                                    <C>
1.      PROPERTY ...............................................................        1
        1.1      Lease of Premises and Phase I Property; Existing Lease ........        1
        1.2      Landlord's Reserved Rights ....................................        1
        1.3      First Refusal Right ...........................................        2

2.      TERM ...................................................................        3
        2.1      Term ..........................................................        3
        2.2      [Omitted.] ....................................................        3
        2.3      Condition of Premises; Tenant Improvements ....................        3
                 (a)      "As Is" Condition ....................................        3
                 (b)      New Mezzanine Area ...................................        4
                 (c)      New Lobby Area .......................................        4
        2.4      [Omitted.] ....................................................        5
        2.5      Holding Over ..................................................        5
        2.6      Option To Extend Term..........................................        5

3.      RENTAL .................................................................        6
        3.1      Minimum Rental ...............................................         6
                (a)      Rental Amounts ........................................        6
                (b)      Rental Adjustment Due to Change in Square Footage .....        6
                (c)      Rental Amounts During First Extended Term .............        7
                (d)      Rental Amounts During Second Extended Term ............        7
        3.2      Late Charge ...................................................        8

4.      [Omitted.] .............................................................        8

5.      [Omitted.] .............................................................        8

6.      TAXES ..................................................................        8
        6.1      Personal Property .............................................        8
        6.2      Real Property .................................................        8

7.      OPERATING EXPENSES .....................................................        9
        7.1      Payment of Operating Expenses .................................        9
        7.2      Definition Of Operating Expenses ..............................       10
        7.3      Determination Of Operating Expenses ...........................       12
        7.4      Final Accounting For Lease Year ...............................       12
        7.5      Proration .....................................................       13

8.      UTILITIES ..............................................................       13
        8.1      Payment........................................................       13
        8.2      Interruption ..................................................       13
</TABLE>

<PAGE>

<TABLE>
<S>                                                                                     <C>
9.   ALTERATIONS; SIGNS ...........................................................     13
     9.1      Right To Make Alterations ...........................................     13
     9.2      Title To Alterations ................................................     14
        (a)      Landlord's Property ..............................................     14
        (b)      Tenant's Property ................................................     14
        (c)      Removal of Tenant's Property at End of Term ......................     14
        (d)      Items Located in Premises Outside the Phase I Property ...........     15
        (e)      Tenant's Rights to Modify, Etc. and Remove Tenant's Property .....     15
        (f)      Tenant's Right to Encumber Tenant's Property .....................     15
        (g)      Landlord's Purchase Option .......................................     15
     9.3       Tenant Fixtures ....................................................     15
     9.4       No Liens ...........................................................     16
     9.5       Signs ..............................................................     16

10.  MAINTENANCE AND REPAIRS ......................................................     16
     10.1      Landlord's Work ....................................................     16
     10.2      Tenant's Obligation For Maintenance ................................     17
        (a)      Good Order, Condition And Repair .................................     17
        (b)      Landlord's Remedy ................................................     17
        (c)      Condition Upon Surrender .........................................     17

11.  USE OF PREMISES ..............................................................     18
     11.1      Permitted Use ......................................................     18
     11.2      [Omitted.] .........................................................     18
     11.3      No Nuisance ........................................................     18
     11.4      Compliance With Laws ...............................................     18
     11.5      Liquidation Sales ..................................................     18
     11.6      Environmental Matters ..............................................     19

12.  INSURANCE AND INDEMNITY ......................................................     22
     12.1      Insurance ..........................................................     22
     12.2      Quality Of Policies And Certificates ...............................     23
     12.3      Workers' Compensation ..............................................     24
     12.4      Waiver Of Subrogation ..............................................     24
     12.5      Increase In Premiums ...............................................     24
     12.6      Indemnification ....................................................     24
     12.7      Blanket Policy .....................................................     25

13.  SUBLEASE AND ASSIGNMENT ......................................................     25
     13.1      Assignment of Lease and Sublease of Premises .......................     25
     13.2      Rights Of Landlord .................................................     26

14.  RIGHT OF ENTRY AND QUIET ENJOYMENT ...........................................     26
     14.1      Right Of Entry .....................................................     26
     14.2      Quiet Enjoyment ....................................................     27

15.  CASUALTY AND TAKING ..........................................................     27
     15.1      Damage or Destruction ..............................................     27
     15.2      Condemnation .......................................................     28
     15.3      Reservation Of Compensation ........................................     29
     15.4      Restoration Of Improvements ........................................     30

16.  DEFAULT ......................................................................     30
     16.1      Events Of Default ..................................................     30
        (a)      [Omitted.] .......................................................     30
        (b)      Nonpayment .......................................................     30
        (c)      Other Obligations ................................................     30
        (d)      General Assignment ...............................................     30
</TABLE>

                                     - ii -

<PAGE>

<TABLE>
<S>                                                                                     <C>
                (e)    Bankruptcy ..............................................        30
                (f)    Receivership ............................................        31
                (g)    Attachment ..............................................        31
                (h)    Insolvency ..............................................        31
        16.2    Remedies Upon Tenant's Default .................................        31
        16.3    Remedies Cumulative ............................................        32

17.     SUBORDINATION, ATTORNMENT AND SALE .....................................        32
        17.1    Subordination To Mortgage ......................................        32
        17.2    Sale Of Landlord's Interest ....................................        33
        17.3    Estoppel Certificates ..........................................        33
        17.4    Subordination to CC&R's ........................................        33
        17.5    Mortgagee Protection ...........................................        33

18.     SECURITY ...............................................................        34
        18.1    Deposit ........................................................        34

19.     MISCELLANEOUS ..........................................................        34
        19.1    Notices ........................................................        34
        19.2    Successors And Assigns .........................................        35
        19.3    No Waiver ......................................................        35
        19.4    Severability ...................................................        35
        19.5    Litigation Between Parties .....................................        35
        19.6    Surrender ......................................................        35
        19.7    Interpretation .................................................        36
        19.8    Entire Agreement ...............................................        36
        19.9    Governing Law ..................................................        36
        19.10   No Partnership .................................................        36
        19.11   Financial Information ..........................................        36
        19.12   Costs ..........................................................        37
        19.13   Time ...........................................................        37
        19.14   Rules And Regulations ..........................................        37
        19.15   Brokers ........................................................        37
        19.16   Memorandum Of Lease ............................................        37
        19.17   Corporate Authority ............................................        37
        19.18   Execution and Delivery .........................................        37
        19.19   Survival .......................................................        37
        19.20   Parking ........................................................        37
</TABLE>

                                EXHIBITS

EXHIBIT A               Real Property Description

EXHIBIT A-1             Phase I Property (Plan)

EXHIBIT B               Site Plan

EXHIBIT C               Future Entrance Lobby

                                    - iii -

<PAGE>

                                      LEASE

      THIS LEASE ("Lease") is made and entered into as of July 1, 2001, by and
between BRITANNIA POINTE GRAND LIMITED PARTNERSHIP, a Delaware limited
partnership ("Landlord"), and COR THERAPEUTICS, INC., a Delaware corporation
("Tenant").

                          THE PARTIES AGREE AS FOLLOWS:

                                   1. PROPERTY

      1.1   Lease of Premises and Phase I Property; Existing Lease.

            (a) Landlord leases to Tenant and Tenant hires and leases from
Landlord, on the terms, covenants and conditions hereinafter set forth, the
following office and laboratory premises (hereinafter collectively called the
"Premises") which consist of approximately 136,242 square feet and are located
on the real property described as the "Phase I Property" in Exhibit A attached
hereto and depicted as such in Exhibit A-1 attached hereto (the "Phase I
Property") in South San Francisco, California: (i) the one-story building
commonly known as 256 East Grand Avenue; (ii) the two-story building commonly
known as 260 East Grand Avenue; (iii) Suites 20, 26, 35, 45, 50 and 70 in the
one-story building commonly known as 250 East Grand Avenue; and (iv) the
westerly portion of the two-story building commonly known as 270 East Grand
Avenue. The Phase I Property is part of the office and research and development
center commonly known as Britannia Pointe Grand Business Park located at East
Grand Avenue and Harbor Way in the City of South San Francisco, County of San
Mateo, State of California on the real property which is more particularly
described as the "Center" in Exhibit A attached hereto (the "Center"). The
location of the Premises in the Center is depicted on the site plan attached
hereto as Exhibit B (the "Site Plan"). The Premises and other improvements
presently existing on the Phase I Property are sometimes referred to
collectively herein as the "Phase I Improvements." The parking areas, driveways,
sidewalks, landscaped areas and other portions of the Center that lie outside
the exterior walls of the buildings now or hereafter existing from time to time
in the Center, as depicted in Exhibit A-1 and in the Site Plan and as hereafter
modified by Landlord from time to time in accordance with the provisions of this
Lease, are sometimes referred to herein as the "Common Areas." Tenant already
occupies the entire Premises pursuant to a Standard Form Industrial Net Lease
dated as of September 23, 1988 between NC Land Associates Limited Partnership, a
Delaware limited partnership, and COR Therapeutics, Inc., a California
corporation, as amended from time to time (the "Existing Lease"). Effective July
1, 2001, this Lease supersedes the Existing Lease for all purposes. Tenant's
continuing occupancy of the Premises shall be governed solely by the provisions
of this Lease, and the Existing Lease shall be of no further force or effect,
except that the rights and obligations of Landlord and Tenant with respect to
the Premises for periods prior to July 1, 2001 shall continue to be governed by
the Existing Lease.

            (b) As an appurtenance to Tenant's leasing of the Premises pursuant
to Section 1.1(a). Landlord hereby grants to Tenant, for the benefit of Tenant
and its employees, suppliers, shippers, customers and invitees, during the term
of this Lease, the non-exclusive right to use in common with others entitled to
such use, (i) those portions of the Common Areas improved from time to time for
use as parking areas, driveways, sidewalks, landscaped areas, or for other
common purposes, and (ii) all access easements and similar rights and privileges
relating to or appurtenant to the Center and created or existing from time to
time under any access easement agreements, declarations of covenants, conditions
and restrictions, or other written agreements now or hereafter of record with
respect to the Center, subject however to any limitations applicable to such
rights and privileges under applicable law, under this Lease and/or under the
written agreements creating such rights and privileges.

      1.2   Landlord's Reserved Rights. To the extent reasonably necessary to
permit Landlord to exercise any rights of Landlord and discharge any obligations
of Landlord under this Lease. Landlord shall have, in addition to the right of
entry set forth in Section 16.1 hereof, the

<PAGE>

following rights: (i) to make changes to the Common Areas, including, without
limitation, changes in the location, size or shape of any portion of the Common
Areas, and to relocate parking spaces in the Center and in the Common Areas,
provided that except on a temporary basis to the extent permitted under clause
(ii) of this sentence, (A) Landlord shall not materially decrease the number of
such parking spaces in areas of the Phase I Property generally adjacent to the
Premises as shown on Exhibit A-1 and on the Site Plan, and (B) Landlord shall
not permit the ratio of parking spaces in the Center to fall below 3.0 spaces
for each 1.000 square feet of space in the various buildings existing from time
to time in the Center (except to the extent, if any, that such ratio may fall
below 3.0 spaces per 1,000 square feet by an amount solely reflecting the
creation of additional square footage in the Center, without additional parking
and subject to receipt of any required governmental variances or approvals, by
reason of the construction of the mezzanine area contemplated in Section 2.3(b)
and/or the new lobby area contemplated in Section 2.3(c)); (ii) to close
temporarily any of the Common Areas for maintenance or other reasonable
purposes, provided that reasonable parking and reasonable access to the Premises
remain available; (iii) to construct, alter or add to other buildings and Common
Area improvements in the Center (including, but not limited to, construction of
site improvements, buildings and Common Area improvements on portions of the
Center and/or on adjacent properties owned by Landlord from time to time); (iv)
to build in areas adjacent to the Center and to add such areas to the Center or
operate such areas, for maintenance, access, parking and other purposes, on an
integrated basis with the Phase I Property and/or the Center; (v) to use the
Common Areas while engaged in making additional improvements, repairs or
alterations to the Center or any portion thereof or to any adjacent properties
owned by Landlord from time to time; and (vi) to do and perform such other acts
with respect to the Common Areas and the Center as may be necessary or
appropriate; provided, however, that notwithstanding anything to the contrary in
this Section 1.2. Landlord's exercise of its rights hereunder shall not cause
any material diminution of Tenant's rights, nor any material increase of
Tenant's obligations, under this Lease or with respect to the Phase I
Improvements.

      1.3   First Refusal Right.

            (a) For purposes of this Section 1.3, the term "First Refusal Space"
shall mean, as the context may require, any one or more of the following four
spaces individually or all four of such spaces collectively: (i) the space of
approximately 10,462 square feet commonly known as 250 East Grand Avenue, Suite
65 and presently occupied by Farmers Insurance; (ii) the space of approximately
6,489 square feet commonly known as 250 East Grand Avenue, Suite 90 and
presently occupied by Gryphon Sciences; (iii) the space of approximately 24,725
presently occupied by ViroLogic, Inc. on the easterly end of the building
commonly known as 270 East Grand Avenue; and (iv) the building commonly known as
280 East Grand Avenue, presently occupied by Cytokinetics, Inc. and containing
approximately 50,195 square feet (the "280 East Grand Building"). The four
spaces constituting the First Refusal Space are designated as such on the Site
Plan.

            (b) Landlord shall not lease all or any portion of the First Refusal
Space at any time during the term of this Lease (including any duly elected
extension terms) except in compliance with the procedure set forth in Section
1.3(c) hereof; provided, however, that the foregoing restriction shall not apply
during any period in which Tenant is in default (beyond any applicable cure
periods) under this Lease; provided further, that the foregoing restriction
shall not apply to any renewal or extension options duly elected by the
applicable tenant or any successor tenant pursuant to a contractual renewal or
extension option set forth in the lease documents governing the respective
portions of the First Refusal Space on the date of this Lease, but such
restriction shall apply to any future lease amendments or grants of renewal or
extension rights with respect to any portion of the First Refusal Space that
would have the effect of either extending the term of any existing occupancy of
any portion of the First Refusal Space beyond the term presently specified in
the lease documents governing such portion, or granting renewal or extension
rights beyond those presently set forth in the applicable lease documents with
respect to any portion of the First Refusal Space; and provided further, that
the foregoing restriction shall not apply to any leasing, subleasing or other
occupancy by Raven Pharmaceuticals. Inc. of all or any portion of the space
described in clause (iii) of Section 1.3(a),

                                     - 2 -

<PAGE>

whether pursuant to the sublease presently in effect between ViroLogic, Inc. and
Raven Pharmaceuticals, Inc. or otherwise, provided that such leasing, subleasing
or other occupancy by Raven Pharmaceuticals, inc. shall not in any event be
authorized to extend beyond June 30, 2003.

            (c) If Landlord intends during the term of this Lease (including any
duly elected extension terms) to lease all or any portion of the First Refusal
Space, and if Tenant is not then in default (beyond any applicable cure periods)
under this Lease, then Landlord shall give to Tenant written notice of such
intention (the "Offer Notice"), specifying the material terms on which Landlord
proposes to lease the First Refusal Space or applicable portion thereof (the
"Offered Space") and offering to Tenant the opportunity to lease the Offered
Space on the terms specified in the Offer Notice. The time period within which
Tenant is entitled to accept such offer by written notice to Landlord (the
"Offer Period"), measured from the date of Tenant's receipt of the Offer Notice,
shall be ten (10) business days, except that if the Offered Space is all or
substantially all of the 280 East Grand Building, then the Offer Period shall be
thirty (30") days unless Tenant has previously received and failed to accept an
Offer Notice with respect to such Offered Space in the 280 East Grand Building
and Landlord is thereafter, within one hundred eighty (180) days after
expiration of the Offer Period for such prior Offer Notice, coming back to
Tenant with a further Offer Notice reflecting terms more favorable to the lessee
than the terms offered in the prior Offer Notice, in which event the Offer
Period for such further Offer Notice shall be ten (10) business days. Upon
timely acceptance of an Offer Notice by Tenant, the Offered Space shall be
leased to Tenant on the terms set forth in the Offer Notice and on the
additional terms and provisions set forth herein (except to the extent
inconsistent with the terms set forth in the Offer Notice) and the parties shall
promptly execute an amendment to this Lease adding the Offered Space to the
Premises and making any appropriate amendments to provisions of this Lease to
reflect different rent and other obligations applicable to the Offered Space
under the terms of the Offer Notice. If Tenant does not accept Landlord's offer
within the allotted time. Landlord shall thereafter have the right to lease the
Offered Space to a third party at any time within one hundred eighty (180) days
after the expiration of the Offer Period, at a minimum rental and on other terms
and conditions not more favorable to the lessee than the minimum rental and
other terms offered to Tenant in the Offer Notice. If Landlord does not
thereafter lease the Offered Space to a third party within one hundred eighty
(180) days as contemplated in the preceding sentence, or if Landlord does lease
the Offered Space to a third party within such 180-day period but the Offered
Space thereafter again becomes available during the term of this Lease
(including any duly elected extension terms), then in either such event Landlord
shall be required to comply again with the provisions of this Section 1.3 prior
to any further leasing of the Offered Space.

                                    2. TERM

      2.1   Term. The term of this Lease shall commence on July 1, 2001 (the
"Commencement Date") and shall end, unless sooner terminated or extended as
hereinafter provided, on June 30, 2011 (the "Termination Date").

      2.2   [Omitted.]

      2.3   Condition of Premises; Tenant Improvements.

            (a) "As Is" Condition. Tenant, being the present occupant of the
Premises pursuant to the Existing Lease, acknowledges that it is familiar with
the physical condition of the Premises, that it will accept and occupy the
Premises under this Lease in "AS IS" condition as the Premises exist on the date
of this Lease, and that Landlord shall have no obligation to improve, repair or
prepare the Premises, prior to the Commencement Date or, except as otherwise
expressly set forth in this Lease, after the Commencement Date, for occupancy by
Tenant under this Lease. TENANT ACKNOWLEDGES THAT EXCEPT AS EXPRESSLY SET FORTH
IN THIS LEASE. NEITHER LANDLORD NOR ANY AGENT OF LANDLORD HAS MADE ANY
REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, AS TO

                                     - 3 -

<PAGE>

THE PRESENT OR FUTURE SUITABILITY OF THE PREMISES OR THE PHASE 1 IMPROVEMENTS
FOR THE CONDUCT OF TENANT'S BUSINESS OR PROPOSED BUSINESS THEREON.

            (b) New Mezzanine Area: Tenant has requested Landlord's permission
to construct, in Tenant's discretion, a mezzanine area of approximately 8,000
square feet in the portion of the Premises commonly known as 260 East Grand
Avenue, approximately in the location designated as "Future Mezzanine Premises"
on the Site Plan.

                  (i) Landlord hereby approves and consents to such
construction, in concept, subject to (A) completion of such improvements by
Tenant at Tenant's sole expense (except as otherwise provided in subparagraph
(b)(ii) hereof) and in compliance with all the requirements of Article 9 hereof,
including (but not limited to) submission of all plans and specifications for
Landlord's review and approval, which approval shall not be unreasonably
withheld or delayed, and (B) Landlord's receipt of a variance from the City of
South San Francisco or other applicable governmental authorities with respect to
the Center's compliance with applicable parking requirements following
construction of such mezzanine area. Landlord hereby agrees to use at Tenant's
request, reasonable efforts to obtain such a variance if and when Tenant advises
Landlord that Tenant wishes to proceed with construction of such mezzanine area,
and Landlord shall bear the expense of all fees and costs incurred by Landlord
in connection with Landlord's application for such a variance.

                  (ii) Landlord agrees to pay to Tenant, within thirty (30) days
after issuance to Tenant of a certificate of occupancy (or its equivalent) for
such mezzanine area and delivery by Tenant to Landlord of lien waivers
reasonably satisfactory to Landlord from the contractor(s) performing such
construction, the sum of Two Hundred Thousand Dollars ($200,000) as a
construction allowance towards Tenant's costs for construction of the shell and
structural components of such mezzanine area.

                  (iii) From and after the date Tenant first occupies the
substantially completed mezzanine area, the mezzanine area shall be deemed to be
part of the Premises and the square footage of the mezzanine area (as determined
by Landlord's architect, measuring to the exterior faces of the walls defining
or enclosing such mezzanine area) shall be added to the square footage of the
Premises for purposes of adjusting Tenant's minimum rent obligation under
Section 3.1(b) and Tenant's Operating Expense Share under Section 7.1(b).

            (c) New Lobby Area. Tenant has requested Landlord's consent to
and/or participation in the construction, in Tenant's discretion, of a new,
enclosed lobby area of approximately 2.500 square feet on the northerly side of
the building commonly known as 250 East Grand Avenue, approximately in the
location designated as "Future Entrance Lobby - Premises" on Exhibit C attached
hereto and incorporated herein by this reference.

                  (i) Landlord hereby approves and consents to such
construction, in concept, subject to Landlord's receipt of a variance from the
City of South San Francisco or other applicable governmental authorities with
respect to the Center's compliance with applicable parking requirements
following construction of such lobby area. Landlord hereby agrees to use, at
Tenant's request and at Landlord's expense, reasonable efforts to obtain such a
variance if and when Tenant notifies Landlord that Tenant wishes to proceed with
construction of such lobby area.

                  (ii) If and when Tenant notifies Landlord of Tenant's desire
to proceed with the construction of the enclosed lobby area and Landlord obtains
the necessary parking variance as described above, (A) Landlord (or, if Landlord
and Tenant mutually agree, Tenant) shall diligently construct, at Landlord's
sole expense, in accordance with plans and specifications prepared by Landlord's
architect and approved by Landlord and Tenant (which approval shall not be
unreasonably withheld or delayed by either party), the cold shell enclosing the
new lobby area (i.e.. exterior walls, slab, roof, windows and entrance doors),
any necessary site preparation work and any exterior paving, landscaping or
other sitework, and (B) Tenant shall construct, at

                                     - 4 -

<PAGE>

Tenant's sole expense, in compliance with all the requirements of Article 9
hereof, including (but not limited to) submission of all plans and
specifications for Landlord's review and approval, all interior finishes and
nonstructural portions of such lobby area, other than the portion of the work
for which Landlord is responsible under clause (A) of this sentence. If Landlord
and Tenant mutually agree that Tenant shall construct some or all of the shell
work described in clause (A) of the preceding sentence at Landlord's expense,
then Landlord shall prepare the applicable plans and specifications as described
in such clause (A), the contractor selected by Tenant shall be subject to
Landlord's prior written approval (not to be unreasonably withheld), the
construction budget and economic terms of Tenant's contract with such approved
contractor shall be subject to Landlord's prior written approval (not to be
unreasonably withheld), and during the course of construction Landlord shall pay
to Tenant or to Tenant's contractor, as Tenant may direct, within twenty (20)
days after receipt of a written payment request and reasonable supporting
documentation (including, but not limited to, lien waivers reasonably
satisfactory to Landlord from the contractor(s) performing the applicable work)
from Tenant from time to time at reasonable intervals as mutually agreed by
Landlord and Tenant, the amount of all costs and expenses reasonably incurred by
Tenant in connection with the construction of such shell work.

                  (iii) From and after the date the enclosed lobby area is
substantially completed and is first placed in use, the lobby area shall be
deemed to be part of the Premises and the square footage of the lobby area (as
determined by Landlord's architect, measuring to the exterior faces of exterior
walls and to the dripline of any exterior overhangs) shall be added to the
square footage of the Premises for purposes of adjusting Tenant's minimum rent
obligation under Section 3.1(b) and Tenant's Operating Expense Share under
Section 7.l(b).

      2.4   [Omitted.]

      2.5   Holding Over. If Tenant holds possession of the Premises or any
portion thereof after the term of this Lease with Landlord's written consent,
then except as otherwise specified in such consent, Tenant shall become a tenant
from month to month at one hundred ten percent (110%) of the rental and
otherwise upon the terms herein specified for the period immediately prior to
such holding over and shall continue in such status until the tenancy is
terminated by either party upon not less than thirty (30) days prior written
notice. If Tenant holds possession of the Premises or any portion thereof after
the term of this Lease without Landlord's written consent, then Landlord in its
sole discretion may elect (by written notice to Tenant) to have Tenant become a
tenant either from month to month or at will, at one hundred fifty percent
(150%) of the rental (prorated on a daily basis for an at-will tenancy, if
applicable) and otherwise upon the terms herein specified for the period
immediately prior to such holding Over, or may elect to pursue any and all legal
remedies available to Landlord under applicable law with respect to such
unconsented holding over by Tenant. Tenant shall indemnify and hold Landlord
harmless from any loss, damage, claim, liability, cost or expense (including
reasonable attorneys' fees) resulting from any delay by Tenant in surrendering
the Premises or any portion thereof (except to the extent such delay is with
Landlord's prior written consent), including but not limited to any claims made
by a succeeding tenant by reason of such delay. Acceptance of rent by Landlord
following expiration or termination of this Lease shall not constitute a renewal
of this Lease.

      2.6   Option To Extend Term. Tenant shall have the option to extend the
term of this Lease, at the minimum rental set forth in Section 3.1 (c) and (d)
and otherwise upon all the terms and provisions set forth herein with respect to
the initial term of this Lease, for up to two (2) additional periods of five (5)
years each, the first commencing upon the expiration of the initial term hereof
and the second commencing upon the expiration of the first extended term, if
any. Exercise of such option with respect to the first such extended term shall
be by written notice to Landlord at least nine (9) months and not more than
twelve (12) months prior to the expiration of the initial term hereof: exercise
of such option with respect to the second extended term, if the first extension
option has been duly exercised, shall be by like written notice to Landlord at
least nine (9) months and not more than twelve (12) months prior to the
expiration of the first extended term hereof. If Tenant is in default hereunder,
beyond any applicable notice and cure periods, on the date of such notice or on
the date any extended term is to commence, then the

                                     - 5 -

<PAGE>

exercise of the option shall be of no force or effect, the extended term shall
not commence and this Lease shall expire at the end of the then current term
hereof (or at such earlier time as Landlord may elect pursuant to the default
provisions of this Lease). If Tenant properly exercises one or more extension
options under this Section, then all references in this Lease (other than in
this Section 2.6) to the "term" of this Lease shall be construed to include the
extension term(s) thus elected by Tenant. Except as expressly set forth in this
Section 2.6. Tenant shall have no right to extend the term of this Lease beyond
its prescribed term.

                                    3. RENTAL

      3.1   Minimum Rental.

            (a) Rental Amounts. Tenant shall pay to Landlord as minimum rental
for the Premises, in advance, without deduction, offset, notice or demand, on or
before the Commencement Date and on or before the first day of each subsequent
calendar month of the initial term of this Lease, the following amounts per
month:

<TABLE>
<CAPTION>
  Months                            Monthly Minimum Rental
  ------                            ----------------------
<C>                              <C>
7/01 - 12/01                     $ 212,537.52 ($1.560/sq ft)
1/02 - 12/02                       261,584.64 ($1.920/sq ft)
1/03 - 12/03                       271,121.58 ($1.990/sq ft)
1/04 - 12/04                       283,383.36 ($2.080/sq ft)
1/05 - 12/05                       479,571.84 ($3.520/sq ft)
1/06 - 12/06                       498,781.96 ($3.661/sq ft)
1/07 - 12/07                       518,673.29 ($3.807/sq ft)
1/08 - 12/08                       539,518.32 ($3.960/sq ft)
1/09 - 12/09                       561,044.56 ($4.118/sq ft)
1/10 - 12/10                       583,524.49 ($4.283/sq ft)
1/11 - 6/11                        606,821.87 ($4.454/sq ft)
</TABLE>

If the obligation to pay minimum rental hereunder commences on other than the
first day of a calendar month or if the term of this Lease terminates on other
than the last day of a calendar month, the minimum rental for such first or last
month of the term of this Lease, as the case may be, shall be prorated based on
the number of days the term of this Lease is in effect during such month. If an
increase in minimum rental becomes effective on a day other than the first day
of a calendar month, the minimum rental for that month shall be the sum of the
two applicable rates, each prorated for the portion of the month during which
such rate is in effect.

            (b) Rental Adjustment Due to Change in Square footage. The minimum
rental amounts specified in this Section 3.1 are based upon an agreed area of
136,242 square feet for the Premises as they exist on the Commencement Date. If
the area of the Premises increases during the initial term of this Lease as a
result of the construction of the new mezzanine area as contemplated in Section
2.3(b) and/or the construction of the new lobby area as contemplated in Section
2.3(c). then beginning on the date the applicable construction is substantially
completed and the applicable new area becomes available for use or is actually
used by Tenant in the ordinary course of its business, the minimum monthly rent
for the remainder of the initial term of this Lease shall be increased, for each
month, by an amount equal to the square footage of the newly constructed area
(measured in accordance with Section 2.3(b)(iii) or 2.3(c)(iii), as applicable)
multiplied by the applicable rental rate per square foot as set forth in Section
3.1(a) above. In the event of any such increase in the area of the Premises
during any extended term of this Lease, the minimum monthly rent during such
extended term (as otherwise determined pursuant to Section 3.1(c) or 3.1(d), as
applicable) shall be increased on a similar basis in strict proportion to the
increase in the size of the Premises as a result of the newly constructed area
being added to the Premises. Any rental increases due to a change in the square
footage of the Premises as a result of Tenant's exercise of a first refusal
right under Section 1.3 hereof with

                                     - 6 -

<PAGE>

respect to any of the First Refusal Space shall be determined and implemented in
accordance with the provisions of Section 1.3 and the applicable Offer Notice
thereunder.

            (c) Rental Amounts During First Extended Term. If Tenant properly
exercises its right to extend the term of this Lease pursuant to Section 2.6
hereof, the minimum rental during the first year of the first extended term
shall be equal to the fair market rental value of the Premises (as defined
below), including any cost-of-living adjustments or other rental increase
provisions then customary in the City of South San Francisco for comparable
commercial leases, determined as of the commencement of such extended term in
accordance with this paragraph. Upon Landlord's receipt of a proper notice of
Tenant's exercise of its option to extend the term of this Lease, the parties
shall have sixty (60) days in which to agree on the initial fair market rental
(including any applicable rental increase provisions) for the Premises at the
commencement of the first extended term for the uses permitted hereunder. If the
parties agree on such initial fair market rental and rental increase provisions
(if any), they shall execute an amendment to this Lease stating the amount of
the applicable minimum monthly rental and any applicable rental increase
provisions. If the parties are unable to agree on such rental (including any
applicable rental increase provisions) within such sixty (60) day period, then
within fifteen (15) days after the expiration of such period each party, at its
cost and by giving notice to the other party, shall appoint a real estate
appraiser with at least five (5) years experience appraising similar commercial
properties in northeastern San Mateo County to appraise and set the initial fair
market rental and any applicable rental increase provisions for the Premises at
the commencement of the first extended term in accordance with the provisions of
this Section 3.1(c). If either party fails to appoint an appraiser within the
allotted time, the single appraiser appointed by the other party shall be the
sole appraiser. If an appraiser is appointed by each party and the two
appraisers so appointed are unable to agree upon an initial fair market rental
(and any appropriate rental increase provisions) within thirty (30) days after
the appointment of the second, the two appraisers shall appoint a third
similarly qualified appraiser within ten (10) days after expiration of such
30-day period; if they are unable to agree upon a third appraiser, then either
party may, upon not less than five (5) days notice to the other party, apply to
the Presiding Judge of the San Mateo County Superior Court for the appointment
of a third qualified appraiser. Each party shall bear its own legal fees in
connection with appointment of the third appraiser and shall bear one-half of
any other costs of appointment of the third appraiser and of such third
appraiser's fee. The third appraiser, however selected, shall be a person who
has not previously acted for either party in any capacity. Within thirty (30)
days after the appointment of the third appraiser, a majority of the three
appraisers shall set the initial fair market rental and any applicable rental
increase provisions for the first extended term and shall so notify the parties.
If a majority are unable to agree within the allotted time, then (i) the three
appraised initial fair market rentals shall be added together and divided by
three and the resulting quotient shall be the initial fair market rental for the
first extended term, and (ii) the applicable rental increase provision shall be
equal to the mathematical average (or the nearest reasonable approximation
thereto) of the two rental increase provisions that are most closely comparable,
which determinations shall be binding on the parties and shall be enforceable in
any further proceedings relating to this Lease. For purposes of this Section
3.1(c), the "fair market rental" of the Premises shall be determined with
reference to the then prevailing market rental rates for properties in the City
of South San Francisco with shell and office, laboratory and research and
development improvements and site (common area) improvements comparable to those
then existing in the Premises and in the Center, taking into account for such
determination all tenant improvements then existing in the Premises (including,
but not limited to, all fixtures, equipment and laboratory improvements in place
in the Premises on the Commencement Date) other than alterations, improvements
or equipment which were constructed or installed by Tenant at its sole expense
and which Tenant has a right or obligation to remove from the Premises at the
expiration of this Lease pursuant to the provisions of Article 9 hereof.

            (d) Rental Amounts During Second Extended Term. If Tenant properly
exercises its right to a second extended term of this Lease pursuant to Section
2.6 hereof, the minimum rental and any applicable rental increase provisions
during such second extended term shall be determined in the same manner provided
in the preceding paragraph for the first

                                      - 7 -

<PAGE>

extended term, except that the determination shall be made as of the
commencement of the second extended term.

      3.2   Late Charge. If Tenant fails to pay rental or other amounts due
Landlord hereunder on or before the fifth (5th) day after such rental or other
amount is due. such unpaid amounts shall bear interest for the benefit of
Landlord at a rate equal to the lesser of fifteen percent (15%) per annum or the
maximum rate permitted by law, from the date due to the date of payment. In
addition to such interest, Tenant shall pay to Landlord a late charge in an
amount equal to six percent (6%) of any installment of minimum rental and any
other amounts due Landlord if not paid in full on or before the fifth (5th) day
after such rental or other amount is due. Tenant acknowledges that late payment
by Tenant to Landlord of rental or other amounts due hereunder will cause
Landlord to incur costs not contemplated by this Lease, including, without
limitation, processing and accounting charges and late charges which may be
imposed on Landlord by the terms of any loan relating to the Center or any
portion thereof. Tenant further acknowledges that it is extremely difficult and
impractical to fix the exact amount of such costs and that the late charge set
forth in this Section 3.2 represents a fair and reasonable estimate thereof.
Acceptance of any late charge by Landlord shall not constitute a waiver of
Tenant's default with respect to overdue rental or other amounts, nor shall such
acceptance prevent Landlord from exercising any other rights and remedies
available to it. Acceptance of rent or other payments by Landlord shall not
constitute a waiver of late charges or interest accrued with respect to such
rent or other payments or any prior installments thereof, nor of any other
defaults by Tenant, whether monetary or non-monetary in nature, remaining
uncured at the time of such acceptance of rent or other payments.

                                 4. [Omitted.]

                                 5. [Omitted.]

                                    6. TAXES

      6.1   Personal Property. Tenant shall be responsible for and shall pay
prior to delinquency all taxes and assessments levied against or by reason of
(a) any and all alterations, additions and items installed or placed on or in
the Premises and taxed as personal property rather than as real property, and/or
(b) all personal property, trade fixtures and other property placed by Tenant on
or about the Premises. Upon request by Landlord, Tenant shall furnish Landlord
with satisfactory evidence of Tenant's payment thereof. If at any time during
the term of this Lease any of said alterations, additions or personal property,
whether or not belonging to Tenant, shall be taxed or assessed as part of the
Center, then such tax or assessment shall be paid by Tenant to Landlord within
fifteen (15) days after presentation by Landlord of copies of the tax bills in
which such taxes and assessments are included and shall, for the purposes of
this Lease, be deemed to be personal property taxes or assessments under this
Section 6.1.

      6.2   Real Property. To the extent any real property taxes and assessments
on any portions of the Center (including, but not limited to, the Improvements
or any portion thereof) leased or occupied solely by Tenant are assessed
directly to Tenant, Tenant shall be responsible for and shall pay prior to
delinquency all such taxes and assessments levied against the applicable
portions of the Center. Upon request by Landlord, Tenant shall furnish Landlord
with satisfactory evidence of Tenant's payment thereof. To the extent the Center
and/or Improvements are taxed or assessed to Landlord following the Commencement
Date, such real property taxes and assessments shall constitute Operating
Expenses (as that term is defined in Section 7.2 of this Lease) and shall be
paid in accordance with the provisions of Article 7 of this Lease.

                                     - 8 -

<PAGE>

                              7. OPERATING EXPENSES

      7.1   Payment of Operating Expenses.

            (a) Tenant shall pay to Landlord, at the time and in the manner
hereinafter set forth, as additional rental, an amount equal to twenty-four and
twenty-one hundredths percent (24.21%) ("Tenant's Operating Cost Share") of the
Operating Expenses defined in Section 7.2; provided, however, that the Tenant's
Operating Cost Share set forth in the preceding portion of this sentence shall
apply only to expenses that are determined and allocated by Landlord on a
Center-wide basis, subject to any adjustments required under any other
applicable provisions of this Section 7.1, and that Tenant's Operating Cost
Share shall be seventy-six and fifty-seven hundredths percent (76.57%) with
respect to any Operating Expenses defined in Section 7.2 that are reasonably
allocable solely to the Phase I Property. As of the date of this Lease. Landlord
represents that the four buildings in which the Premises are located are the
only buildings located on the Phase I Property and that Landlord's current
practice is to determine and allocate all Operating Expenses (including, but not
limited to, real and personal property taxes and assessments, insurance,
building maintenance, property management, landscape maintenance and irrigation,
and parking area maintenance and lighting) on a stand-alone basis to the Phase I
Property.

            (b) Tenant's Operating Cost Share as specified in paragraph (a) of
this Section with respect to Operating Expenses which are determined and
allocated on a Center-wide basis is based upon an area of 136,242 square feet
for the Premises and upon an aggregate area of 562,859 square feet for the
existing buildings owned by Landlord in the Center as depicted in the Site Plan.
Tenant's Operating Cost Share as specified in paragraph (a) of this Section with
respect to Operating Expenses which are determined and allocated solely to the
Phase I Property is based upon an area of 136,242 square feet for the Premises
and upon an aggregate area of 177,938 square feet for the existing buildings on
the Phase I Property. If the actual area of the buildings on the Phase I
Property from time to time or of the buildings owned from time to time by
Landlord in the Center and consolidated with the buildings in which the Premises
are located for operation, maintenance, common area and Operating Expense
purposes, as applicable, as such area is determined in good faith by Landlord's
architect on the same basis of measurement under which the Premises have been
determined to contain 136,242 square feet (from the exterior faces of exterior
walls and from the dripline of any overhangs, except that in the case of any
two-story recesses or overhangs, the area to the dripline of the overhang is
counted as part of the area of the first story but not as part of the area of
the second story), differs from the assumed figures set forth above (including,
but not limited to, any such difference arising from the construction of
additional buildings in the Center as contemplated in Section 7.1(c) hereof), or
if the area of the Premises changes from time to time pursuant to the
construction of additional areas of the Premises pursuant to Section 2.3(b)
and/or 2.3(c) and/or pursuant to Tenant's exercise of a first refusal right
pursuant to Section 1.3 hereof, then Tenant's Operating Cost Share as it applies
to Operating Expenses that are determined and allocated on a Center-wide basis
or that are determined and allocated solely with respect to the Phase I
Property, as applicable, shall be adjusted to reflect the actual areas so
determined as they exist from time to time; provided, however, that in the event
Tenant exercises a first refusal right with respect to the 280 East Grand
Building, Landlord hereby advises Tenant that it is presently Landlord's
practice to account for all Operating Expenses attributable or allocable to the
separate legal parcel on which the 280 East Grand Building is located on a
stand-alone basis and to allocate such Operating Expenses one hundred percent
(100%) to the tenant(s) of the 280 East Grand Building.

            (c) If Landlord at any time constructs additional buildings in the
Center or on any adjacent property owned by Landlord and operated, for common
area purposes, on an integrated basis with the Center, then Tenant's Operating
Cost Share as it applies to Operating Expenses that are determined and allocated
on a Center-wide basis shall be adjusted to be equal to the percentage
determined by dividing the gross square footage of the Premises as they exist
from time to time by the gross square footage of all buildings located in the
Center or on any applicable adjacent property owned by Landlord as described
above. In determining such percentage, a building shall be taken into account
from and after the date on which a tenant first

                                     - 9 -

<PAGE>

enters into possession of the building or a portion thereof, and the good faith
determination of the gross square footage of any such building by Landlord's
architects shall be final and binding upon the parties.

      7.2     Definition Of Operating Expenses.

            (a) Subject to the exclusions and provisions hereinafter contained,
the term "Operating Expenses" shall mean the total costs and expenses incurred
by or allocable to Landlord for management, operation and maintenance of the
Improvements, the Center, the buildings in the Center, and the real property on
which the Center is located (or, in the case of items that are determined and
allocated on a stand-alone basis as described in Section 7.1. that portion of
the Center that consists of the separate legal parcel or parcels containing the
buildings in which the Premises are located), including, without limitation,
costs and expenses of (i) insurance (including earthquake and environmental
insurance), property management, landscaping, and the operation, repair and
maintenance of buildings and Common Areas; (ii) all utilities and services;
(iii) real and personal property taxes and assessments or substitutes therefor
levied or assessed against the Center or any part thereof, including (but not
limited to) any possessory interest, use, business, license or other taxes or
fees, any taxes imposed directly on rents or services, any assessments or
charges for police or fire protection, housing, transit, open space, street or
sidewalk construction or maintenance or other similar services from time to time
by any governmental or quasi-governmental entity, and any other new taxes on
landlords in addition to taxes now in effect; (iv) supplies, equipment,
utilities and tools used in management, operation and maintenance of the Center;
(v) expenditures for capital improvements to the Center, the Improvements or the
buildings in the Center, amortized over a reasonable period determined in
accordance with generally accepted accounting principles applied on a consistent
basis, (aa) which reduce or will cause future reduction of other items of
Operating Expenses for which Tenant is otherwise required to contribute or (bb)
which are required by law, ordinance, regulation or order of any governmental
authority or (cc) of which Tenant has use or which benefit Tenant; and (vi) any
other costs (including, but not limited to, any parking or utilities fees or
surcharges) allocable to or paid by Landlord, as owner of the Center, the
buildings therein or the Improvements, pursuant to any applicable laws,
ordinances, regulations or orders of any governmental or quasi-governmental
authority or pursuant to the terms of any declarations of covenants, conditions
and restrictions now or hereafter affecting the Center or any other property
over which Tenant has non-exclusive use rights as contemplated in Section 1.1
(b) hereof. Operating Expenses shall not include any costs attributable to
Landlord's Work, nor any costs attributable to the initial construction of the
buildings in the Center or of Common Area improvements in the Center. The
distinction between items of ordinary operating maintenance and repair and items
of a capital nature shall be made in accordance with generally accepted
accounting principles applied on a consistent basis or in accordance with tax
accounting principles, as determined in good faith by Landlord's accountants.

            (b) Notwithstanding anything to the contrary contained in this
Lease, the following shall not be included within Operating Expenses:

                  (i) Costs of maintenance or repair of the roof membrane for
any building, except during periods (if any) in which costs of maintenance or
repair of the roof membrane for the buildings in which the Premises are located
are likewise included as an Operating Expense (rather than being incurred
directly by Tenant or passed through directly to Tenant);

                  (ii) Leasing commissions, attorneys' fees, costs,
disbursements, and other expenses incurred in connection with negotiations or
disputes with tenants, or in connection with leasing, renovating or improving
space for tenants or other occupants or prospective tenants or other occupants
of the Center or of any other property owned by Landlord;

                  (iii) The cost of any service sold to any tenant (including
Tenant) or other occupant for which Landlord is entitled to be reimbursed as an
additional charge or rental over and above the basic rent and operating expenses
payable under the lease with that tenant;

                                     - 10 -

<PAGE>

                  (iv) Any depreciation on the buildings in which the Premises
are located or on any other improvements in the Center or on any other property
owned by Landlord;

                  (v) Expenses in connection with services or other benefits of
a type that are not offered or made available to Tenant but that are provided to
another tenant of the Center or of any other property owned by Landlord;

                  (vi) Costs incurred due to Landlord's violation of any terms
or conditions of this Lease or of any other lease relating to the buildings in
which the Premises are located or to any other portion of the Center or of any
other property owned by Landlord:

                  (vii) Overhead profit increments paid to any subsidiary or
affiliate of Landlord for management or other services on or to the Center or
any portion thereof or any other property owned by Landlord, or for supplies or
other materials to the extent that the cost of the services, supplies or
materials exceeds the cost that would have been paid had the services, supplies
or materials been provided by unaffiliated parties on a competitive basis;

                  (viii) All interest, loan fees and other carrying costs
related to any mortgage or deed of trust or related to any capital item, and all
rental and other amounts payable under any ground or underlying lease, or under
any lease for any equipment ordinarily considered to be of a capital nature
(except (A) janitorial equipment which is not affixed to the applicable
buildings and/or (B) equipment the cost of which, if purchased, would be
considered an amortizable Operating Expense under the provisions of this Section
7.2. notwithstanding the capital nature of such equipment);

                  (ix) Any compensation paid to clerks, attendants or other
persons in commercial concessions operated by Landlord;

                  (x) Advertising and promotional expenditures:

                  (xi) Costs of repairs and other work occasioned by fire,
windstorm or other casualty of an insurable nature, except to the extent of any
applicable deductible amounts under insurance actually carried by Landlord;

                  (xii) Any costs, fines or penalties incurred due to violations
by Landlord of any governmental rule or authority or of this Lease or any other
lease of any portion of the Center or any other property owned by Landlord, or
due to Landlord's negligence or willful misconduct;

                  (xiii) Management fees allocable to the Phase I Property to
the extent they exceed the following percentages of the gross income (rent and
Operating Expenses) received by Landlord with respect to the Phase I Property
during the applicable period: (A) from the Commencement Date through December
31,2004, two and one half percent (2.5%); and (B) from January 1,2005 through
the remaining term of this Lease (including any extension term(s)), one and one
half percent (1.5%);

                  (xiv) Costs for sculpture, paintings or other objects of art,
and for any insurance thereon or extraordinary security in connection therewith;

                  (xv) Wages, salaries or other compensation paid to any
executive employees above the grade of building manager;

                  (xvi) The cost of correcting any building code or other
violations which were violations prior to the Commencement Date;

                  (xvii) The cost of containing, removing or otherwise
remediating any contamination of the Center (including the underlying land and
groundwater) by any toxic or hazardous materials (including, without limitation,
asbestos and PCBs); and

                                     - 11 -

<PAGE>
                  (xviii) During any period when the Center is owned by a person
or entity which is not a person or entity controlling, controlled by or under
common control with either Landlord or Slough Estates USA Inc., earthquake
and/or environmental insurance premiums in excess of rates that are commercially
reasonable under then existing market conditions.

      7.3   Determination Of Operating Expenses. Tenant is already paying
estimated Operating Expenses, pursuant to the Existing Lease, for calendar year
2001 based on estimates previously furnished by Landlord to Tenant. During the
last month of each calendar year of the term of this Lease ("Lease Year"), or as
soon thereafter as practical. Landlord shall provide Tenant notice of Landlord's
estimate of the Operating Expenses for the ensuing Lease Year or applicable
portion thereof. On or before the first day of each month during each Lease Year
or applicable portion thereof, beginning on the Commencement Date, Tenant shall
pay to Landlord Tenant's Operating Cost Share of the portion of such estimated
Operating Expenses allocable (on a prorata basis) to such month; provided,
however, that if such notice is not given in the last month of a Lease Year,
Tenant shall continue to pay on the basis of the prior year's estimate, if any,
until the month after such notice is given. If at any time or times it appears
to Landlord that the actual Operating Expenses will vary from Landlord's
estimate by more than five percent (5%), Landlord may, by notice to Tenant,
revise its estimate for such year and subsequent payments by Tenant for such
year shall be based upon such revised estimate.

      7.4   Final Accounting For Lease Year.

            (a) Within ninety (90) days after the close of each Lease Year, or
as soon after such 90-day period as practicable. Landlord shall deliver to
Tenant a statement of Tenant's Operating Cost Share of the Operating Expenses
for such Lease Year prepared by Landlord from Landlord's books and records,
which statement shall be final and binding on Landlord and Tenant (except as
provided in Section 7.4(b)). If on the basis of such statement Tenant owes an
amount that is more or less than the estimated payments for such Lease Year
previously made by Tenant, Tenant or Landlord, as the case may be, shall pay the
deficiency to the other party within thirty (30) days after delivery of the
statement. Failure or inability of Landlord to deliver the annual statement
within such ninety (90) day period shall not impair or constitute a waiver of
Tenant's obligation to pay Operating Expenses, or cause Landlord to incur any
liability for damages.

            (b) At any time within three (3) months after receipt of Landlord's
annual statement of Operating Expenses as contemplated in Section 7.4(a), Tenant
shall be entitled, upon reasonable written notice to Landlord and during normal
business hours at Landlord's office or such other places as Landlord shall
designate, to inspect and examine those books and records of Landlord relating
to the determination of Operating Expenses for the immediately preceding Lease
Year covered by such annual statement or, if Tenant so elects by written notice
to Landlord, to request an independent audit of such books and records. The
independent audit of the books and records shall be conducted by a certified
public accountant acceptable to both Landlord and Tenant or, if the parties are
unable to agree, by a certified public accountant appointed by the Presiding
Judge of the San Mateo County Superior Court upon the application of either
Landlord or Tenant (with notice to the other party). In either event, such
certified public accountant shall be one who is not then employed in any
capacity by Landlord or Tenant or by any of their respective affiliates. The
audit shall be limited to the determination of the amount of Operating Expenses
for the subject Lease Year, and shall be based on generally accepted accounting
principles and tax accounting principles, consistently applied. If it is
determined, by mutual agreement of Landlord and Tenant or by independent audit,
that the amount of Operating Expenses billed to or paid by Tenant for the
applicable Lease Year was incorrect, then the appropriate party shall pay to the
other party the deficiency or overpayment, as applicable, within thirty (30)
days after the final determination of such deficiency or overpayment. All costs
and expenses of the audit shall be paid by Tenant unless the audit shows that
Landlord overstated Operating Expenses for the subject Lease Year by more than
five percent (5%), in which case Landlord shall pay all costs and expenses of
the audit. Each party agrees to maintain the confidentiality of the findings of
any audit in accordance with the provisions of this Section 7.4.

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<PAGE>

      7.5   Proration. If the Commencement Date falls on a day other than the
first day of a Lease Year or if this Lease terminates on a day other than the
last day of a Lease Year, then the amount of Operating Expenses payable by
Tenant with respect to such first or last partial Lease Year shall be prorated
on the basis which the number of days during such Lease Year in which this Lease
is in effect bears to 365. The termination of this Lease shall not affect the
obligations of Landlord and Tenant pursuant to Section 7.4 to be performed after
such termination.

                                8.    UTILITIES

      8.1   Payment. Commencing with the Commencement Date and thereafter
throughout the term of this Lease, Tenant shall pay, before delinquency, all
charges for water, gas, heat, light, electricity, power, sewer, telephone, alarm
system, janitorial and other services or utilities supplied to or consumed in or
with respect to the Premises (other than any separately metered costs for water,
electricity or other services or utilities furnished with respect to the Common
Areas, which costs, to the extent paid by Landlord, shall constitute Operating
Expenses under Section 7.2 hereof), including any taxes on such services and
utilities. It is the intention of the parties that all such services shall be
separately metered to the Premises. In the event that any of such services
supplied to the Premises are not separately metered, then the amount thereof
shall be an item of Operating Expenses and shall be paid as provided in Article
7.

      8.2   Interruption. There shall be no abatement of rent or other charges
required to be paid hereunder and Landlord shall not be liable in damages or
otherwise for interruption or failure of any service or utility furnished to or
used with respect to the Premises or the Center because of accident, making of
repairs, alterations or improvements, severe weather, difficulty or inability in
obtaining services or supplies, labor difficulties or any other cause.
Notwithstanding the foregoing provisions of this Section 8.2, however, in the
event of any interruption or failure of any service or utility to the Premises
that (i) is caused in whole or in material part by the active negligence or
willful misconduct of Landlord or its agents or employees and (ii) continues for
more than three (3) business days and (iii) materially impairs Tenant's ability
to use the Premises for their intended purposes hereunder, then following such
three (3) business day period. Tenant's obligations for payment of rent and
other charges under this Lease shall be abated in proportion to the degree of
impairment of Tenant's use of the Premises or applicable portion thereof, and
such abatement shall continue until Tenant's use of the Premises is no longer
materially impaired thereby.

                              9. ALTERATIONS; SIGNS

      9.1   Right To Make Alterations. Tenant shall make no alterations,
additions or improvements to the Premises, the buildings in which the Premises
are located or the Center. other than (i) alterations, additions or improvements
to Tenant's Property (as defined in, and subject to the provisions of, Section
9.2 below), and/or (ii) other interior non-structural alterations costing less
than Fifty Thousand Dollars ($50,000.00) in the aggregate during any twelve (12)
month period, without the prior written consent of Landlord, which consent shall
not be unreasonably withheld or delayed. All such alterations, additions and
improvements shall be completed with due diligence in a first-class workmanlike
manner, in compliance with plans and specifications approved in writing by
Landlord and in compliance with all applicable laws, ordinances, rules and
regulations, and to the extent Landlord's consent is not otherwise required
hereunder for such alterations, additions or improvements, Tenant shall give
prompt written notice thereof to Landlord. Tenant shall cause any contractors
engaged by Tenant for work in the Premises or on the Property to maintain public
liability and property damage insurance, and other customary insurance, with
such terms and in such amounts as Landlord may reasonably require, naming as
additional insureds Landlord and any of its partners, shareholders, property
managers and lenders designated by Landlord for this purpose, and shall furnish
Landlord with certificates of insurance or other evidence that such coverage is
in effect. Notwithstanding any other provisions of this Section 9.1, under no
circumstances shall Tenant make any structural alterations or improvements, or
any substantial changes to the roof or substantial equipment

                                     - 13 -

<PAGE>

installations on the roof, or any substantial changes or alterations to the
building systems, without Landlord's prior written consent (which consent shall
not be unreasonably withheld or delayed). If Tenant so requests in seeking
Landlord's consent to any alterations, additions or improvements, Landlord shall
specify in granting such consent whether Landlord intends to require that Tenant
remove such alterations, additions or improvements (or any specified portions
thereof) upon expiration or termination of this Lease. Landlord shall receive no
fee for supervision, profit, overhead or general conditions in connection with
any alterations, additions or improvements constructed or installed by Tenant
under this Lease.

      9.2   Title To Alterations. All alterations, additions and improvements
existing in the Premises on the Commencement Date or thereafter installed in, on
or about the Premises or the Center (except as otherwise expressly provided in
this Section 9.2) shall become part of the Center and the real property on which
it is located and shall become the property of Landlord, unless Landlord elects,
in the case of any alterations, additions or improvements installed after the
Commencement Date, to require Tenant to remove the same upon the termination of
this Lease (subject to the provisions of Section 9.2(c) below).

            (a) Landlord's Property. The parties specifically agree that the
alterations, additions and improvements which are or shall be part of the Center
and are or shall be the property of Landlord shall include (but not be limited
to) (i) built-in coldrooms, (ii) air lines, plumbing, electrical wiring and
other similar systems associated with any of Tenant's (A) built-in coldrooms,
(B) laboratory casework, (C) vacuum pumps, (D) compressors, and/or (E) water
purification and deionized water systems, (iii) plumbing, electrical wiring and
other similar systems associated with Tenant's animal water system and located
within walls, ceilings or floors, and (iv) wiring and jacks associated with
Tenant's telephone systems, computer network systems and security systems, but
shall not include Tenant's Property (as defined in Section 9.2(b) below) except
to the extent purchased by Landlord pursuant to Section 9.2(g), if applicable.

            (b) Tenant's Property. With respect to any portions of the Premises
as they exist from time to time that are located on the Phase I Property, the
term "Tenant's Property" shall mean all of the following items: (i) movable
personal property, office furniture and/or modular office furniture systems,
movable equipment and trade fixtures; (ii) lab benches, built-in fume hoods,
plumbing fixtures and other laboratory casework (collectively, the "Option
Property"), but excluding air lines, plumbing, electrical wiring and other
similar systems associated with any of such laboratory casework and/or built-in
fume hoods; (iii) compressors, excluding air lines, plumbing, electrical wiring
and other similar systems associated with any of such compressors; (iv) vacuum
pumps, excluding plumbing, electrical wiring and other similar systems
associated with any of such vacuum pumps; (v) water purification systems and/or
deionized water systems, excluding plumbing, electrical wiring and other similar
systems associated with any of such water purification or deionized water
systems; (vi) auxiliary generators and transfer switches; (vii) telephone
systems and desk sets, excluding wiring and jacks; (viii) computer network
systems, excluding wiring and jacks; (ix) security system, excluding wiring and
jacks; (x) cage and rack washers; (xi) glassware washers; (xii) autoclaves;
(xiii) Edstram animal water system, excluding plumbing, electrical wiring and
other similar systems associated with such animal water system; (xiv)
freestanding coldrooms; and (xv) movable fume hoods.

            (c) Removal of Tenant's Property at End of Term. Notwithstanding
anything to the contrary contained in the foregoing provisions, the parties
specifically agree that the Option Property shall not become the property of
Landlord unless, and then only to the extent that, Landlord exercises its
purchase option in accordance with Section 9.2(g) below. Tenant shall have the
right to remove at the termination or expiration of this Lease, subject to any
specific limitations set forth in this Article 9. any or all of Tenant's
Property. Tenant shall promptly repair any damage caused by its removal of any
of Tenant's Property during or at the expiration of the term of this Lease.
Notwithstanding any other provisions of this Article 9, however, if Tenant
requests Landlord's written consent to any alterations, additions or
improvements under Section 9.1 hereof after the Commencement Date and, in
requesting such

                                     - 14 -
<PAGE>

consent, asks that Landlord specify whether Landlord will require removal of
such alterations, additions or improvements upon termination or expiration of
this Lease, then Landlord shall not be entitled to require such removal unless
Landlord specified its intention to do so at the time of granting of Landlord's
consent to the requested alterations, additions or improvements.

            (d) Items Located in Premises Outside the Phase I Property. With
respect to any portions of the Premises as they exist from time to time that are
located outside the Phase I Property (such as, for example, the 280 East Grand
Building if hereafter added to the Premises pursuant to Section 1.3 hereof), the
term "Tenant's Property" shall not include any lab benches, built-in fume hoods,
plumbing fixtures and other laboratory casework (which items shall instead be
deemed upon installation, or upon commencement of Tenant's leasing of such
additional Premises to the extent such items were installed by Landlord or a
predecessor tenant prior to such commencement, to be Landlord's property and to
be part of the Center and of the real property on which it is located) and shall
include items described in any of the other clauses of Section 9.2(b) only to
the extent such items are installed by Tenant in such additional Premises at
Tenant's sole expense.

            (e) Tenant's Rights to Modify. Etc. and Remove Tenant's Property: As
provided in Sections 9.1 and 9.2, but subject to any limitations expressly set
forth in this Article 9, Tenant shall generally have the right throughout the
term of this Lease to install, alter, modify, improve, replace and remove
Tenant's Property without Landlord's consent and shall generally have the right
at the termination or expiration of this Lease to remove Tenant's Property,
provided that Tenant shall, at all times prior to the lapse (if any),
unexercised, of Landlord's purchase option under Section 9.2(g) with respect to
the Option Property, maintain in the Premises a quality and quantity of
laboratory casework, lab benches and built-in fume hoods that is not materially
less than the quality and quantity of such items located in the Premises on the
Commencement Date (subject to the effects of ordinary wear and tear and to the
effects of damage, destruction or other casualty, the latter of which shall be
governed by the provisions of Article 15 hereof).

            (f) Tenant's Right to Encumber Tenant's Property. Tenant shall also
have the right, notwithstanding any other provisions of this Article 9
(including, but not limited to, Landlord's purchase option for the Option
Property pursuant to Section 9.2(g) below), to use Tenant's Property as security
for third-party financing during the term of this Lease, and Landlord agrees to
cooperate in all reasonable respects with any such third-party financing sought
by Tenant against the security of Tenant's Property, including recognition by
Landlord of the lender's right, subject to reasonable conditions, to foreclose
upon and remove Tenant's Property upon a default by Tenant under such financing.

            (g) Landlord's Purchase Option. Landlord shall have the option,
exercisable by written notice to Tenant no less than ninety (90) days before the
expiration of the term of this Lease (or concurrently with any earlier
termination of this Lease by Landlord pursuant to a default by Tenant, if
applicable), to purchase from Tenant (and thereby require Tenant to leave behind
in the Premises upon such expiration or termination, notwithstanding any other
provisions of this Section 9.2) all then existing Option Property for a purchase
price of Six Hundred Fifty Thousand Dollars ($650,000.00) payable to Tenant in
cash concurrently with and in exchange for Tenant's delivery to Landlord of a
bill of sale, in form and substance reasonably satisfactory to Landlord,
conveying to Landlord all such Option Property in its then existing condition,
as is, but free and clear of any liens or encumbrances created by or through
Tenant. If Landlord does not timely exercise such purchase option, then Tenant
shall have the same right to remove the Option Property from the Premises prior
to or upon termination or expiration of this Lease as Tenant has with respect to
the rest of Tenant's Property, subject to any express conditions or restrictions
set forth in this Article 9 with respect to such removal.

      9.3   Tenant Fixtures. Subject to Sections 9.2 and 9.5, Tenant may
install, remove and reinstall Tenant's Property and other trade fixtures without
Landlord's prior written consent, except that installation and removal of any
fixtures which affect the exterior or structural portions of the buildings in
which the Premises are located or the building systems therein shall require

                                     - 15 -

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Landlord's written approval, which approval shall not be unreasonably withheld
or delayed. Subject to the provisions of Section 9.5, the foregoing shall apply
to Tenant's signs, logos and insignia, all of which Tenant shall have the right
to place and remove and replace (a) only with Landlord's prior written consent
as to location, size and composition, which consent shall not be unreasonably
withheld or delayed, and (b) only in compliance with all restrictions and
requirements of applicable law and of any covenants, conditions and restrictions
or other written agreements now or hereafter applicable to the Center. Tenant
shall immediately repair any damage caused by installation and removal of
fixtures under this Section 9.3.

      9.4   No Liens. Tenant shall at all times keep the Premises, the buildings
in which the Premises are located and the Center free from all liens and claims
of any contractors, subcontractors, materialmen, suppliers or any other parties
employed either directly or indirectly by Tenant in construction work on the
Premises or in the Center. Notwithstanding the preceding sentence, Tenant may
contest any claim of lien, but only if, prior to such contest. Tenant either (i)
posts security in the amount of the claim, plus estimated costs and interest, or
(ii) records a bond of a responsible corporate surety in such amount as may be
required to release the lien from the applicable buildings or improvements and
the Center. Tenant shall indemnify, defend and hold Landlord harmless against
any and all liability, loss, damage, cost and other expenses, including, without
limitation, reasonable attorneys' fees, arising out of claims of any lien for
work performed or materials or supplies furnished at the request of Tenant or
persons claiming under Tenant.

      9.5   Signs. Without limiting the generality of the provisions of Section
9.3 hereof. Tenant shall have the right to display its corporate name and logo
on the buildings in which the Premises are located and in front of the principal
entrances to the Premises. subject to Landlord's prior approval as to location,
size, design and composition (which approval shall not be unreasonably withheld
or delayed), subject to the established sign criteria for the Britannia Pointe
Grand Business Park and subject to all restrictions and requirements of
applicable law and of any covenants, conditions and restrictions or other
written agreements now or hereafter applicable to the Center. Landlord hereby
expressly confirms that it has already approved all of Tenant's signage existing
on and about the Premises as of the Commencement Date, and that in the event a
new lobby is constructed as contemplated in Section 2.3(c) above, Landlord will
approve, at Tenant's request, any new exterior signage that is substantially
similar to or reasonably comparable to the signage then maintained, with
Landlord's consent, by other major tenants in the Center.

                           10. MAINTENANCE AND REPAIRS

      10.1  Landlord's Work.

            (a) Landlord shall repair and maintain or cause to be repaired and
maintained the driveways, parking areas, landscaping and other Common Areas of
the Center and the structural roof, roof membrane, exterior walls, foundation
and other structural portions of the buildings in which the Premises are
located. The cost of all work performed by Landlord under this Section 10.1
shall be an Operating Expense hereunder, except to the extent such work (i) is
required due to the negligence of Landlord, (ii) is a capital expenditure not
includible as an Operating Expense under Section 7.2 hereof, (iii) is required
due to the negligence or willful misconduct of Tenant or its agents, employees
or invitees (in which event Tenant shall bear the full cost of such work
pursuant to the indemnification provided in Section 12.6 hereof, subject to the
release set forth in Section 12.4 hereof), or (iv) involves repair or
maintenance of the roof membrane on any of the applicable buildings (in which
event there shall be charged back directly to Tenant, as additional rent and not
as an Operating Expense, but subject to the same limitations set forth for
Operating Expenses in Section 7.2 for purposes of determining what are capital
items and what portion, if any, of capital items can properly be allocated to a
particular year or other applicable period, a prorata share of the cost of such
repair or maintenance calculated on the basis of the percentage of the
applicable building that is occupied by Tenant). Tenant knowingly and
voluntarily waives the right to make repairs at Landlord's expense, except to
the

                                     - 16 -

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extent permitted by Section 10.1 (b) below, or to offset the cost thereof
against rent, under any law, statute, regulation or ordinance now or hereafter
in effect.

            (b) If Landlord fails to perform any repairs or maintenance required
to be performed by Landlord on the buildings in which the Premises are located
under Section 10.1(a) and such failure continues for thirty (30) days or more
after Tenant gives Landlord written notice of such failure (or, if such repairs
or maintenance cannot reasonably be performed within such 30-day period, then if
Landlord fails to commence performance within such 30-day period and thereafter
to pursue such performance diligently to completion), then Tenant shall have the
right to perform such repairs or maintenance and Landlord shall reimburse Tenant
for the reasonable cost thereof within fifteen (15) days after written notice
from Tenant of the completion and cost of such work, accompanied by copies of
invoices or other reasonable supporting documentation. Under no circumstances,
however, shall Tenant have any right to offset the cost of any such work against
rent or other charges falling due from time to time under this Lease.

      10.2  Tenant's Obligation For Maintenance.

            (a) Good Order, Condition And Repair. Except as provided in Section
10.1 hereof, and except for damage caused by Landlord or its agents, employees
or contractors (which shall be the sole responsibility of Landlord, subject to
the release set forth in Section 12.4 hereof) or by an event of casualty or
condemnation (which shall be governed by Article 15 hereof). Tenant at its sole
cost and expense shall keep and maintain in good and sanitary order, condition
and repair the Premises and every part thereof, wherever located, including but
not limited to the signs, interior, ceiling, electrical system, plumbing system,
telephone and communications systems of the buildings in which the Premises are
located, the HVAC equipment and related mechanical systems serving the Premises
(for which equipment and systems Tenant shall enter into a service contract with
a person or entity designated or approved by Landlord), all doors, door checks,
windows, plate glass, door fronts, exposed plumbing and sewage and other utility
facilities, fixtures, lighting, wall surfaces, floor surfaces and ceiling
surfaces of the Premises and all other interior repairs, foreseen and
unforeseen, with respect to the Premises, as required.

            (b) Landlord's Remedy. If Tenant, after notice from Landlord, fails
to make or perform promptly any repairs or maintenance which are the obligation
of Tenant hereunder, Landlord shall have the right, but shall not be required,
to enter the Premises and make the repairs or perform the maintenance necessary
to restore the Premises to good and sanitary order, condition and repair.
Immediately on demand from Landlord, the cost of such repairs shall be due and
payable by Tenant to Landlord.

            (c) Condition Upon Surrender. At the expiration or sooner
termination of this Lease, Tenant shall surrender the Premises and the
Improvements, including any additions, alterations and improvements thereto,
broom clean, in good and sanitary order, condition and repair, ordinary wear and
tear excepted, first, however, removing all goods and effects of Tenant and all
and fixtures and items required to be removed or specified to be removed at
Landlord's election pursuant to this Lease (including, but not limited to, any
such removal required as a result of an election duly made by Landlord to
require such removal as contemplated in Section 9.2), and repairing any damage
caused by such removal. Tenant shall not have the right to remove fixtures or
equipment if Tenant is in default hereunder, beyond any applicable cure period,
unless Landlord specifically waives this provision in writing. Tenant expressly
waives any and all interest in any personal property and trade fixtures not
removed from the Premises by Tenant at the expiration or termination of this
Lease, agrees that any such personal property and trade fixtures may, at
Landlord's election, be deemed to have been abandoned by Tenant, and authorizes
Landlord (at its election and without prejudice to any other remedies under this
Lease or under applicable law) to remove and either retain, store or dispose of
such property at Tenant's cost and expense, and Tenant waives all claims against
Landlord for any damages resulting from any such removal, storage, retention or
disposal.

                                     - 17 -

<PAGE>

                               11. USE OF PREMISES

      11.1  Permitted Use. Subject to Sections 11.3, 11.4 and 11.6 hereof.
Tenant shall use the Premises solely for a laboratory research and development
facility, including (but not limited to) wet chemistry and biology labs, clean
rooms, light manufacturing, storage and use of toxic and radioactive materials
(subject to the provisions of Section 11.6 hereof), storage and use of
laboratory animals, administrative offices, and other lawful purposes reasonably
related to or - incidental to such specified uses (subject in each case to
receipt of all necessary approvals from the City of South San Francisco and
other governmental agencies having jurisdiction over the Premises), and for no
other purpose.

      11.2  [Omitted.]

      11.3  No Nuisance. Tenant shall not use the Premises or the Center for or
carry on or permit within the Center or any part thereof any offensive, noisy or
dangerous trade, business, manufacture, occupation, odor or fumes, or any
nuisance or anything against public policy, nor interfere with the rights or
business of Landlord in the Premises or the Center, nor commit or allow to be
committed any waste in, on or about the Center. Tenant shall not do or permit
anything to be done in or about the Center, nor bring nor keep anything therein,
which will in any way cause the Center to be uninsurable with respect to the
insurance required by this Lease or with respect to standard fire and extended
coverage insurance with vandalism, malicious mischief and riot endorsements.

      11.4  Compliance With Laws. Tenant shall not use the Premises or the
Center or permit the Premises or the Center to be used in whole or in part for
any purpose or use that is in violation of any applicable laws, ordinances,
regulations or rules of any governmental agency or public authority. Tenant
shall keep the Premises and Improvements therein equipped with all safety
appliances required by law, ordinance or insurance on the Center, or any order
or regulation of any public authority, because of Tenant's particular use of the
Premises and the Center. Tenant shall procure all licenses and permits required
for Tenant's use of the Premises and the Center. Tenant shall use the Premises
and the Center in strict accordance with all applicable ordinances, rules, laws
and regulations and shall comply with all requirements of all governmental
authorities now in force or which may hereafter be in force pertaining to the
use of the Premises and the Center by Tenant, including, without limitation,
regulations applicable to noise, water, soil and air pollution, and making
such nonstructural alterations and additions thereto in the Premises or the
Center as may be required from time to time by such laws, ordinances, rules,
regulations and requirements of governmental authorities or insurers of the
Center (collectively, "Requirements") because of Tenant's construction of
improvements in or other particular use of the Premises or the Center. Any
structural alterations or additions required from time to time by applicable
Requirements because of Tenant's construction of improvements in the Premises or
other particular use of the Premises or the Center shall, at Landlord's
election, either (i) be made by Tenant, at Tenant's sole cost and expense, in
accordance with the procedures and standards set forth in Section 9.1 for
alterations by Tenant, or (ii) be made by Landlord at Tenant's sole cost and
expense, in which event Tenant shall pay to Landlord as additional rent, within
ten (10) days after demand by Landlord, an amount equal to all reasonable costs
incurred by Landlord in connection with such alterations or additions. The
judgment of any court, or the admission by Tenant in any proceeding against
Tenant, that Tenant has violated any law, statute, ordinance or governmental
rule, regulation or requirement shall be conclusive of such violation as between
Landlord and Tenant.

      11.5  Liquidation Sales. Tenant shall not conduct or permit to be
conducted any auction, bankruptcy sale, liquidation sale, or going out of
business sale, in, upon or about the Premises or the Center, whether said
auction or sale be voluntary, involuntary or pursuant to any assignment for the
benefit of creditors, or pursuant to any bankruptcy or other insolvency
proceeding.

                                      - 18 -

<PAGE>

      11.6  Environmental Matters.

            (a) For purposes of this Section, "hazardous substance" shall mean
the substances included within the definitions of the term "hazardous substance"
under (i) the Comprehensive Environmental Response, Compensation and Liability
Act of 1980, as amended, 42 U.S.C. Sections 9601 et seq., and the regulations
promulgated thereunder, as amended, (ii) the California Carpenter-Presley-Tanner
Hazardous Substance Account Act, California Health & Safety Code Sections 25300
et seq., and regulations promulgated thereunder, as amended, (iii) the
Hazardous Materials Release Response Plans and Inventory Act, California Heath
& Safety Code Sections 25500 et seq., and regulations promulgated thereunder, as
amended, and (iv) petroleum; "hazardous waste" shall mean (i) any waste listed
as or meeting the identified characteristics of a "hazardous waste" under the
Resource Conservation and Recovery Act of 1976, 42 U.S.C. Sections 6901 et seq.,
and regulations promulgated pursuant thereto, as amended (collectively, "RCRA").
(ii) any waste meeting the identified characteristics of "hazardous waste,"
"extremely hazardous waste" or "restricted hazardous waste" under the California
Hazardous Waste Control Law, California Health & Safety Code Sections 25100 et
seq., and regulations promulgated pursuant thereto, as amended (collectively,
the "CHWCL"), and/or (iii) any waste meeting the identified characteristics of
"medical waste" under California Health & Safety Code Sections 25015-25027.8,
and regulations promulgated thereunder, as amended; and "hazardous waste
facility" shall mean a hazardous waste facility as defined under the CHWCL.

            (b) Without limiting the generality of the obligations set forth in
Section 11.4 of this Lease:

                  (i) Tenant shall not cause or permit any hazardous substance
or hazardous waste to be brought upon, kept, stored or used in or about the
Premises or the Center without the prior written consent of Landlord, which
consent shall not be unreasonably withheld, except that Tenant, in connection
with its permitted use of the Premises as provided in Section 11.1, may keep,
store and use materials that constitute hazardous substances which are customary
for such permitted use, provided such hazardous substances are kept, stored and
used in quantities which are customary for such permitted use and are kept,
stored and used in full compliance with clauses (ii) and (iii) immediately
below.

                  (ii) Tenant shall comply with all applicable laws, rules,
 regulations, orders, permits, licenses and operating plans of any governmental
 authority with respect to the receipt, use, handling, generation,
 transportation, storage, treatment and/or disposal of hazardous substances or
 wastes by Tenant or its agents or employees, and Tenant will provide Landlord
 with copies of all permits, licenses, registrations and other similar documents
 that authorize Tenant to conduct any such activities in connection with its
 authorized use of the Premises and the Center from time to time.

                  (iii) Tenant shall not (A) operate on or about the Premises or
the Center any facility required to be permitted or licensed as a hazardous
waste facility or for which interim status as such is required, nor (B) store
any hazardous wastes on or about the Premises or the Center for ninety (90) days
or more, nor (C) conduct any other activities on or about the Premises or the
Center that could result in the Premises or the Center being deemed to be a
"hazardous waste facility" (including, but not limited to, any storage or
treatment of hazardous substances or hazardous wastes which could have such a
result).

                  (iv) Tenant shall comply with all applicable laws, rules,
regulations, orders and permits relating to underground storage tanks installed
by Tenant or its agents or employees or at the request of Tenant (including any
installation, monitoring, maintenance, closure and/or removal of such tanks) as
such tanks are defined in California Health & Safety Code Section 25281 (x),
including, without limitation, complying with California Health & Safety Code
Sections 25280-25299.7 and the regulations promulgated thereunder, as amended.
Tenant shall furnish to Landlord copies of all registrations and permits issued
to or held by Tenant from time to time for any and all underground storage tanks
located on or under the Premises or the Center.

                                     - 19 -

<PAGE>

                  (v) If applicable, Tenant shall provide Landlord in writing
the following information and/or documentation within thirty (30) days after the
Commencement Date, and shall update such information at least annually, on or
before each anniversary of the Commencement Date, to reflect any change in or
addition to the required information and/or documentation (provided, however,
that in the case of the materials described in subparagraphs (B), (C) and (E)
below, Tenant shall not be required to deliver copies of such materials to
Landlord but shall maintain copies of such materials to such extent and for such
periods as may be required by applicable law and shall permit Landlord or its
representatives to inspect and copy such materials during normal business hours
at any time and from time to time upon reasonable notice to Tenant):

                        (A) A list of all hazardous substances and/or wastes
that Tenant receives, uses, handles, generates, transports, stores, treats or
disposes of from time to time in connection with its operations on the Premises
and in the Center.

                        (B) All Material Safety Data Sheets ("MSDS's"), if
any, required to be completed with respect to operations of Tenant at the
Premises and in the Center from time to time in accordance with Title 26,
California Code of Regulations Section 8-5194 or 42 U.S.C. Section 11021, or
any amendments thereto, and any Hazardous Materials Inventory Sheets that detail
the MSDS's.

                        (C) All hazardous waste manifests (as defined in Title
26, California Code of Regulations Section 22-66481), if any, that Tenant is
required to complete from time to time in connection with its operations at the
Premises and in the Center.

                        (D) A copy of any Hazardous Materials Management Plan
required from time to time with respect to Tenant's operations at the Premises
and in the Center, pursuant to California Health & Safety Code Sections 25500 et
seq., and any regulations promulgated thereunder, as amended.

                        (E) Any Contingency Plans and Emergency Procedures
required of Tenant from time to time due to its operations in accordance with
Title 26, California Code of Regulations Section 22-67140 et seq., and any
amendments thereto, and any Training Programs and Records required under Title
26, California Code of Regulations. Section 22-67105, and any amendments
thereto.

                        (F) Copies of any biennial reports to be furnished to
the California Department of Health Services from time to time relating to
hazardous substances or wastes, pursuant to Title 26, California Code of
Regulations, Section 22-66493, and any amendments thereto.

                        (G) Copies of all industrial wastewater discharge
permits issued to or held by Tenant from time to time in connection with its
operations on the Premises and in the Center.

                        (H) Copies of any other lists or inventories of
hazardous substances and/or wastes on or about the Premises and/or the Center
that Tenant is otherwise required to prepare and file from time to time with any
governmental or regulatory authority.

                  (vi) Tenant shall secure Landlord's prior written approval for
any proposed receipt, storage, possession, use, transfer or disposal of
"radioactive materials" or "radiation," as such materials are defined in Title
26, California Code of Regulations Section 17-30100, and/or any other materials
possessing the characteristics of the materials so defined, which approval
Landlord may withhold in its sole and absolute discretion; provided, that such
approval shall not be required for any radioactive materials for which Tenant
has secured prior written approval of the Nuclear Regulatory Commission and
delivered to Landlord a copy of such approval. Tenant, in connection with any
such authorized receipt, storage, possession, use, transfer or disposal of
radioactive materials or radiation, shall:

                                     - 20 -

<PAGE>

                        (A) Comply with all federal, state and local laws,
rules, regulations, orders, licenses and permits issued to or applicable to
Tenant with respect to its business operations on the Premises and in the
Center;

                        (B) Maintain, to such extent and for such periods as may
be required by applicable law, and permit Landlord and its representatives to
inspect during normal business hours at any time and from time to time upon
reasonable notice to Tenant, a list of all radioactive materials or radiation
received, stored, possessed, used, transferred or disposed of by Tenant or in
connection with the operation of Tenant's business on the Premises and in the
Center from time to time, to the extent not already disclosed through delivery
of a copy of a Nuclear Regulatory Commission approval with respect thereto as
contemplated above; and

                        (C) Maintain, to such extent and for such periods as may
be required by applicable law, and permit Landlord or its representatives to
inspect during normal business hours at any time and from time to time upon
reasonable notice to Tenant, all licenses, registration materials, inspection
reports, governmental orders and permits in connection with the receipt,
storage, possession, use, transfer or disposal of radioactive materials or
radiation by Tenant or in connection with the operation of Tenant's business on
the Premises and in the Center from time to time.

                  (vii) Tenant shall comply with any and all applicable laws,
rules, regulations and orders of any governmental authority with respect to the
release into the environment of any hazardous wastes or substances or radiation
or radioactive materials by Tenant or its agents or employees. Tenant shall give
Landlord immediate verbal notice of any unauthorized release of any such
hazardous wastes or substances or radiation or radioactive materials into the
environment, and shall follow such verbal notice with written notice to Landlord
of such release within ten (10) business days after the date Tenant became aware
of such release.

                  (viii) Tenant shall indemnify, defend and hold Landlord
harmless from and against any and all claims, losses (including, but not limited
to loss of rental income), damages, liabilities, costs, legal fees and expenses
of any sort arising out of or relating to (A) any failure by Tenant to comply
with any provisions of this paragraph 11.6(b), or (B) any receipt, use handling,
generation, transportation, storage, treatment, release and/or disposal of any
hazardous substance or waste or any radioactive material or radiation on or
about the Premises or the Center as a proximate result of Tenant's use of the
Premises or the Center or as a result of any intentional or negligent acts or
omissions of Tenant or of any agent, employee or invitee of Tenant.

                  (ix) Tenant shall cooperate with Landlord in furnishing
Landlord with complete information regarding Tenant's receipt, handling, use,
storage, transportation, generation, treatment and/or disposal of any hazardous
substances or wastes or radiation or radioactive materials. Upon request, Tenant
shall grant Landlord reasonable access at reasonable times to the Premises to
inspect Tenant's receipt, handling, use, storage, transportation, generation,
treatment and/or disposal of hazardous substances or wastes or radiation or
radioactive materials, provided that Landlord uses reasonable efforts to avoid
any unreasonable interference with Tenant's business operations in exercising
such access and inspection rights, without thereby being deemed guilty of any
disturbance of Tenant's use or possession and without being liable to Tenant in
any manner.

                  (x) Notwithstanding Landlord's rights of inspection and review
under this paragraph 11.6(b), Landlord shall have no obligation or duty to so
inspect or review, and no third party shall be entitled to rely on Landlord to
conduct any sort of inspection or review by reason of the provisions of this
paragraph 11.6(b).

                  (xi) If Tenant receives, handles, uses, stores, transports,
generates, treats and/or disposes of any hazardous substances or wastes or
radiation or radioactive materials on or about the Premises or the Center at any
time during the term of this Lease, then within

                                     - 21 -

<PAGE>

thirty (30) days after the termination or expiration of this Lease, Tenant at
its sole cost and expense shall obtain and deliver to Landlord an environmental
study, performed by an expert reasonably satisfactory to Landlord, evaluating
the presence or absence of hazardous substances and wastes, radiation and
radioactive materials on and about the Premises and the Center. Such study shall
be based on a reasonable and prudent level of tests and investigations of the
Premises and surrounding areas (if appropriate), which tests shall be conducted
no earlier than the date of termination or expiration of this Lease. Liability
for any remedial actions required or recommended on the basis of such study
shall be allocated in accordance with Sections 11.4, 11.6, 12.6 and other
applicable provisions of this Lease.

            (c) Landlord shall indemnify, defend and hold Tenant harmless from
and against any and all claims, losses, damages, liabilities, costs, legal fees
and expenses of any sort arising out of or relating to (i) the presence on the
Premises or in the Center of any hazardous substances or wastes or radiation or
radioactive materials as of the Commencement Date (other than as a result of any
intentional or negligent acts or omissions of Tenant or of any agent, employee
or invitee of Tenant, or as a result of or in connection with Tenant's prior
business operations on the Premises and in the Center), and /or (ii) any
unauthorized release into the environment (including, but not limited to, the
Premises and/or the Center) of any hazardous substances or wastes or radiation
or radioactive materials to the extent such release results from the negligence
of or willful misconduct or omission by Landlord or its agents or employees.

            (d) The provisions of this Section 11.6 shall survive the
termination of this Lease.

                           12. INSURANCE AND INDEMNITY

      12.1  Insurance.

            (a) Tenant shall procure and maintain in full force and effect at
all times during the term of this Lease, at Tenant's cost and expense,
commercial general liability insurance to protect against liability to the
public, or to any invitee of Tenant or Landlord, arising out of or related to
the use of or resulting from any accident occurring in, upon or about the
Premises, with limits of liability of not less than (i) Two Million Dollars
($2,000,000.00) for injury to or death of one person, (ii) Five Million Dollars
($5,000,000.00) for personal injury or death, per occurrence, and (iii) One
Million Dollars ($1,000,000.00) for property damage, or combined single limit
of liability of not less than Five Million Dollars ($5,000,000.00). Such
insurance shall name Landlord, its general partners, its Managing Agent and any
lender holding a deed of trust on the Center or any portion thereof from time to
time (as designated in writing by Landlord to Tenant from time to time) as
additional insureds thereunder. The amount of such insurance shall not be
construed to limit any liability or obligation of Tenant under this Lease.
Tenant shall also procure and maintain in full force and effect at all times
during the term of this Lease, at Tenant's cost and expense, products/completed
operations coverage in an amount of not less than Five Million Dollars
($5,000,000.00) and on other terms customary in Tenant's industry for companies
engaged in the marketing of products on a scale comparable to that in which
Tenant is engaged from time to time.

            (b) Landlord shall procure and maintain in full force and effect at
all times during the term of this Lease, at Landlord's cost and expense (but
reimbursable as an Operating Expense under Section 7.2 hereof), commercial
general liability insurance to protect against liability arising out of or
related to the use of or resulting from any accident occurring in, upon or about
the Center, with combined single limit of liability of not less than Five
Million Dollars ($5,000,000.00) per occurrence for bodily injury and property
damage.

            (c) Landlord shall procure and maintain in full force and effect at
all times during the term of this Lease, at Landlord's cost and expense (but
reimbursable as an Operating Expense under Section 7.2 hereof), policies of
property insurance providing protection against "all risk of direct physical
loss" (as defined by and detailed in the Insurance Service Office's

                                     - 22 -

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Commercial Property Program "Cause of Loss--Special Form [CP1030]" or its
equivalent) for the shell of the buildings in which the Premises are located and
for the improvements in the Common Areas of the Center, on a full replacement
cost basis (with no co-insurance or, if coverage without co-insurance is not
reasonably available, then on an "agreed amount" basis). Such insurance shall
include earthquake and environmental coverage and shall have such commercially
reasonable deductibles and other terms as Landlord in its reasonable discretion
determines to be appropriate. Landlord shall have no obligation to carry
property damage insurance for Tenant's Property, for Tenant's personal property
or, except as expressly set forth in paragraph (d) below, for any alterations,
additions or improvements installed by Tenant or by any predecessor tenant in
the buildings in which the Premises are located or on or about the Center.

            (d) Landlord shall procure and maintain in full force and effect at
all times during the term of this Lease, at Tenant's cost and expense
(chargeable, in Landlord's discretion, either as an Operating Expense allocable
100% to Tenant or as a direct pass-through to Tenant), policies of property
insurance providing protection against "all risk of direct physical loss" (as
defined by and detailed in the Insurance Service Office's Commercial Property
Program "Cause of Loss-Special Form [CP1030]" or its equivalent) for the tenant
improvements existing in the Premises on the Commencement Date (other than
Tenant's Property, which it shall be Tenant's responsibility to insure pursuant
to paragraph (e) below), on a full replacement cost basis (with no co-insurance
or, if coverage without co-insurance is not reasonably available, then on an
"agreed amount" basis). Such insurance may have such commercially reasonable
deductibles and other terms as Landlord in its reasonable discretion determines
to be appropriate, and shall name both Tenant and Landlord as insureds as their
interests may appear. The coverage required to be maintained under this
paragraph (d) may, in Landlord's discretion, be added to or combined with
Landlord's master policy carried under paragraph (c) above (but, if not actually
carried as part of Landlord's master policy under paragraph (c) above, shall not
carry a premium materially higher than would apply if such coverage were being
carried as part of Landlord's master policy under paragraph (c) above), in which
event Tenant shall be named as an insured only with respect to the portion of
the policy that covers tenant improvements as described in this paragraph (d).
Tenant shall provide to Landlord from time to time, upon request by Landlord
annually or at other reasonable intervals, an updated schedule of values for
such existing tenant improvements, and Landlord shall have no obligation or
liability with respect to any underinsurance of tenant improvements that results
from Tenant's failure to keep Landlord informed from time to time, on a current
basis, of the insurable value of such tenant improvements.

            (e) Tenant shall procure and maintain in full force and effect at
all times during the term of this Lease, at Tenant's cost and expense, policies
of property insurance providing protection against "all risk of direct physical
loss" (as defined by and detailed in the Insurance Service Office's Commercial
Property Program "Cause of Loss-Special Form [CP1030]" or its equivalent) for
Tenant's Property as it exists in the Premises on the Commencement Date and for
all other alterations, additions and improvements installed by Tenant from time
to time in or about the Premises after the Commencement Date (except as Landlord
and Tenant may otherwise mutually agree in writing from time to time), on a full
replacement cost basis (with no co-insurance or, if coverage without
co-insurance is not reasonably available, then on an "agreed amount" basis).
Such insurance may have such commercially reasonable deductibles and other terms
as Tenant in its reasonable discretion determines to be appropriate, and shall
name both Tenant and Landlord as insureds as their interests may appear.

      12.2  Quality Of Policies And Certificates. All policies of insurance
required hereunder shall be issued by responsible insurers and, in the case of
policies carried or required to be carried by Tenant, shall be written as
primary policies not contributing with and not in excess of any coverage that
Landlord may carry. Tenant shall deliver to Landlord copies of policies or
certificates of insurance showing that said policies are in effect. The coverage
provided by such policies shall include the clause or endorsement referred to in
Section 12.4. If Tenant fails to acquire, maintain or renew any insurance
required to be maintained by it under this Article 12 or

                                     - 23 -
<PAGE>

to pay the premium therefor, then Landlord, at its option and in addition to its
other remedies, but without obligation so to do, may procure such insurance, and
any sums expended by it to procure any such insurance on behalf of or in place
of Tenant shall be repaid upon demand, with interest as provided in Section 3.2
hereof. Tenant shall obtain written undertakings from each insurer under
policies required to be maintained by it to notify all insureds thereunder at
least thirty (30) days prior to cancellation of coverage.

      12.3  Workers' Compensation. Tenant shall maintain in full force and
effect during the term of this Lease workers' compensation insurance in at least
the minimum amounts required by law, covering all of Tenant's employees working
on the Premises or in the Center.

      12.4  Waiver Of Subrogation. To the extent permitted by law and without
affecting the coverage provided by insurance required to be maintained
hereunder. Landlord and Tenant each waive any right to recover against the other
with respect to (i) damage to property, (ii) damage to the Premises or the
Center or any part thereof, or (iii) claims arising by reason of any of the
foregoing, but only to the extent that any of the foregoing damages and claims
under clauses (i)-(iii) hereof are covered, and only to the extent of such
coverage, by casualty insurance actually carried or required to be carried
hereunder by either Landlord or Tenant. This provision is intended to waive
fully, and for the benefit of each party, any rights and claims which might give
rise to a right of subrogation in any insurance carrier. Each party shall
procure a clause or endorsement on any casualty insurance policy denying to the
insurer rights of subrogation against the other party to the extent rights have
been waived by the insured prior to the occurrence of injury or loss. Coverage
provided by insurance maintained by Tenant shall not be limited, reduced or
diminished by virtue of the subrogation waiver herein contained.

      12.5  Increase In Premiums. Tenant shall do all acts and pay all expenses
necessary to insure that the Premises are not used for purposes prohibited by
any applicable fire insurance, and that Tenant's use of the Premises and the
Center complies with all requirements necessary to obtain any such insurance. If
Tenant uses or permits the Premises to be used in a manner which increases the
existing rate of any insurance carried by Landlord on the Center and such use
continues for longer than a reasonable period specified in any written notice
from Landlord to Tenant identifying the rate increase and the factors causing
the same, then Tenant shall pay the amount of the increase in premium caused
thereby, and Landlord's costs of obtaining other replacement insurance policies,
including any increase in premium, within ten (10) days after demand therefor by
Landlord.

      12.6  Indemnification.

            (a) Tenant shall indemnify, defend and hold Landlord and its
partners, shareholders, officers, directors, agents and employees harmless from
any and all liability for injury to or death of any person, or loss of or damage
to the property of any person, and all actions, claims, demands, costs
(including, without limitation, reasonable attorneys' fees), damages or expenses
of any kind arising therefrom which may be brought or made against Landlord or
which Landlord may pay or incur by reason of the use, occupancy and enjoyment of
the Premises and the Center by Tenant or any invitees, sublessees, licensees,
assignees, employees, agents or contractors of Tenant or holding under Tenant
from any cause whatsoever other than negligence or willful misconduct or
omission by Landlord, its agents or employees. Landlord and its partners,
shareholders, officers, directors, agents and employees shall not be liable for,
and Tenant hereby waives all claims against such persons for, damages to goods,
wares and merchandise in or upon the Premises or the Center, or for injuries to
Tenant, its agents or third persons in or upon the Premises or the Center, from
any cause whatsoever other than negligence or willful misconduct or omission by
Landlord, its agents or employees. Tenant shall give prompt notice to Landlord
of any casualty or accident in, on or about the Premises or the Center.

            (b) Landlord shall indemnify, defend and hold Tenant and its
partners, shareholders, officers, directors, agents and employees harmless from
any and all liability for injury to or death of any person, or loss of or damage
to the property of any person, and all

                                     - 24 -

<PAGE>

actions, claims, demands, costs (including, without limitation, reasonable
attorneys' fees). damages or expenses of any kind arising therefrom which may be
brought or made against Tenant or which Tenant may pay or incur, to the extent
such liabilities or other matters arise in, on or about the Premises or the
Center by reason of any negligence or willful misconduct or omission by
Landlord, its agents or employees.

      12.7  Blanket Policy. Any policy required to be maintained hereunder may
be maintained under a so-called "blanket policy" insuring other parties and
other locations so long as the amount of insurance required to be provided
hereunder is not thereby diminished.

                           13. SUBLEASE AND ASSIGNMENT

      13.1  Assignment of Lease and Sublease of Premises. Except in the case of
a Permitted Transfer, Tenant shall not have the right or power to assign its
interest in this Lease, or make any sublease of the Premises or any portion
thereof, nor shall any interest of Tenant under this Lease be assignable
involuntarily or by operation of law, without on each occasion obtaining the
prior written consent of Landlord, which consent shall not be unreasonably
withheld or delayed. Any purported sublease or assignment of Tenant's interest
in this Lease requiring but not having received Landlord's consent thereto (to
the extent such consent is required hereunder) shall be void. Without limiting
the generality of the foregoing, Landlord may withhold consent to any proposed
subletting or assignment for which consent is requested solely on the ground, if
applicable, that the use by the proposed subtenant or assignee is reasonably
likely to be incompatible with Landlord's use of any adjacent property owned or
operated by Landlord, unless the proposed use is within the permitted uses
specified in Section 11.1, in which event it shall not be reasonable for
Landlord to object to the proposed use. Except in the case of a Permitted
Transfer, any dissolution, consolidation, merger or other reorganization of
Tenant, or any sale or transfer of substantially all of the stock or assets of
Tenant in a single transaction or series of related transactions, shall be
deemed to be an assignment hereunder and shall be void without the prior written
consent of Landlord as required above. Notwithstanding the foregoing. (i) any
public offering of the common stock of Tenant shall not be deemed to be an
assignment hereunder; (ii) any transfer of Tenant's stock during any period in
which Tenant has a class of stock listed on any recognized securities exchange
or traded in the NASDAQ over-the-counter market shall not be deemed to be an
assignment hereunder; (iii) any transfer of Tenant's stock in connection with a
bona fide financing, capitalization or recapitalization of Tenant shall not be
deemed to be an assignment hereunder, provided that such financing,
capitalization or recapitalization does not result in a material reduction in
Tenant's net worth or materially change the nature of Tenant's ongoing business
as a going concern; and (iv) Tenant shall have the right to assign this Lease or
sublet the Premises or any portion thereof, without Landlord's consent (but with
prior or concurrent written notice by Tenant to Landlord, except to the extent
Tenant is advised by its counsel that such prior or concurrent notice would be
in violation of applicable law, in which event Tenant shall give such written
notice as soon as reasonably possible after the giving of such notice is no
longer in violation of applicable law), to any Affiliate of Tenant, or to any
entity which results from a merger or consolidation with Tenant, or to any
entity which acquires substantially all of the stock or assets of Tenant as a
going concern (hereinafter each a "Permitted Transfer"). For purposes of the
preceding sentence, an "Affiliate" of Tenant shall mean any entity in which
Tenant owns at least a fifty percent (50%) equity interest, any entity which
owns at least a fifty percent (50%) equity interest in Tenant, and/or any entity
which is related to Tenant by a chain of ownership interests involving at least
a fifty percent (50%) equity interest at each level in the chain. Landlord shall
have no right to terminate this Lease in connection with, and shall have no
right to any sums or other economic consideration resulting from, any Permitted
Transfer. Except as expressly set forth in this Section 13.1, however, the
provisions of Section 13.2 shall remain applicable to any Permitted Transfer and
the transferee under such Permitted Transfer shall be and remain subject to all
of the terms and provisions of this Lease.

                                     - 25 -

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      13.2  Rights Of Landlord.

            (a) Consent by Landlord to one or more assignments of this Lease, or
to one or more sublettings of the Premises or any portion thereof, or collection
of rent by Landlord from any assignee or sublessee, shall not operate to exhaust
Landlord's rights under this Article 13, nor constitute consent to any
subsequent assignment or subletting. No assignment of Tenant's interest in this
Lease and no sublease shall relieve Tenant of its obligations hereunder,
notwithstanding any waiver or extension of time granted by Landlord to any
assignee or sublessee, or the failure of Landlord to assert its rights against
any assignee or sublessee, and regardless of whether Landlord's consent thereto
is given or required to be given hereunder. In the event of a default by any
assignee, sublessee or other successor of Tenant in the performance of any of
the terms or obligations of Tenant under this Lease, Landlord may proceed
directly against Tenant without the necessity of exhausting remedies against any
such assignee, sublessee or other successor. In addition, Tenant immediately and
irrevocably assigns to Landlord, as security for Tenant's obligations under this
Lease, all rent from any subletting of all or a part of the Premises as
permitted under this Lease, and Landlord, as Tenant's assignee and as
attorney-in-fact for Tenant, or any receiver for Tenant appointed on Landlord's
application, may collect such rent and apply it toward Tenant's obligations
under this Lease; except that, until the occurrence of an act of default by
Tenant, Tenant shall have the right to collect such rent and to retain all
sublease profits (subject to the provisions of Section 13.2(c), below).

            (b) Upon any assignment of Tenant's interest in this Lease for which
Landlord's consent is required under Section 13.1 hereof, Tenant shall pay to
Landlord, within ten (10) days after receipt thereof by Tenant from time to
time, one-half (1/2) of all cash sums and other economic considerations received
by Tenant in connection with or as a result of such assignment, after first
deducting therefrom (i) any costs incurred by Tenant for leasehold improvements
(including, but not limited to, third-party architectural and space planning
costs) in the Premises in connection with such assignment, (ii) any real estate
commissions and/or reasonable attorneys' fees incurred by Tenant in connection
with such assignment, and (iii) any economic consideration received by Tenant as
bona fide, reasonable compensation for personal property sold or leased by
Tenant to the assignee.

            (c) Upon any sublease of all or any portion of the Premises for
which Landlord's consent is required under Section 13.1 hereof, Tenant shall pay
to Landlord, within ten (10) days after receipt thereof by Tenant from time to
time, one-half (1/2) of all cash sums and other economic considerations received
by Tenant in connection with or as a result of such sublease, after first
deducting therefrom (i) the rental due hereunder for the corresponding period,
prorated (on the basis of the per-square-foot cost paid by Tenant for the entire
Premises for the applicable period under this Lease) to reflect the size of the
subleased portion of the Premises, (ii) any costs incurred by Tenant for
leasehold improvements in the subleased portion of the Premises (including, but
not limited to, third-party architectural and space planning costs) for the
specific benefit of the sublessee in connection with such sublease, amortized
over the term of the sublease, (iii) any real estate commissions and/or
reasonable attorneys' fees incurred by Tenant in connection with such sublease,
amortized over the term of such sublease, and (iv) any economic consideration
received by Tenant as bona fide, reasonable compensation for personal property
sold or leased by Tenant to the sublessee.

                     14. RIGHT OF ENTRY AND QUIET ENJOYMENT

      14.1  Right Of Entry. Landlord and its authorized representatives shall
have the right to enter the Premises at any time during the term of this Lease
during normal business hours and upon not less than twenty-four (24) hours prior
notice, except in the case of emergency (in which event no notice shall be
required and entry may be made at any time), for the purpose of inspecting and
determining the condition of the Premises or for any other proper purpose
including, without limitation, to make repairs, replacements or improvements
which Landlord may deem necessary, to show the Premises to prospective
purchasers, to show the Premises to prospective tenants (but only during the
final year of the term of this Lease), and to post notices

                                     - 26 -

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of nonresponsibility. Landlord shall not be liable for inconvenience, annoyance,
disturbance, loss of business, quiet enjoyment or other damage or loss to Tenant
by reason of making any repairs or performing any work upon the Premises or the
Center or by reason of erecting or maintaining any protective barricades in
connection with any such work, and the obligations of Tenant under this Lease
shall not thereby be affected in any manner whatsoever, provided, however,
Landlord shall use reasonable efforts to minimize the inconvenience to Tenant's
normal business operations caused thereby.

      14.2  Quiet Enjoyment. Landlord covenants that Tenant, upon paying the
rent and performing its obligations hereunder and subject to all the terms and
conditions of this Lease, shall peacefully and quietly have, hold and enjoy the
Premises and the Common Areas of the Center throughout the term of this Lease,
or until this Lease is terminated as provided by this Lease.

                             15. CASUALTY AND TAKING

      15.1  Damage or Destruction.

            (a) If the Premises, or the Common Areas of the Center necessary for
Tenant's use and occupancy of the Premises, are damaged or destroyed in whole or
in part under circumstances in which (i) repair and restoration is permitted
under applicable governmental laws, regulations and building codes then in
effect and (ii) repair and restoration reasonably can be completed within a
period of one (1) year (or, in the case of an occurrence during the last year of
the term of this Lease, within a period of sixty (60) days) following the date
of the occurrence, then Landlord, as to the Common Areas of the Center and the
cold shell of the buildings in which the Premises are located, and Tenant, as to
all other improvements existing in or about the Premises immediately prior to
such occurrence, shall commence and complete, with all due diligence and as
promptly as is reasonably practicable under the conditions then existing, all
such repair and restoration as may be required to return the affected portions
of the Premises and the Center to a condition comparable to that existing
immediately prior to the occurrence. In the event of damage or destruction the
repair of which is not permitted under applicable governmental laws, regulations
and building codes then in effect, if such damage or destruction (despite being
corrected to the extent then permitted under applicable governmental laws,
regulations and building codes) would still materially impair Tenant's ability
to conduct its business in the Premises, then either party may terminate this
Lease as of the date of the occurrence by giving written notice to the other
within thirty (30) days after the date of the occurrence; if neither party
timely elects such termination, or if such damage or destruction does not
materially impair Tenant's ability to conduct its business in the Premises, then
this Lease shall continue in full force and effect, except that there shall be
an equitable adjustment in monthly minimum rental and of Tenant's Operating Cost
Share of Operating Expenses, based upon the extent to which Tenant's ability to
conduct its business in the Premises is impaired, and Landlord and Tenant
respectively shall restore the Common Areas and the cold shell of the applicable
buildings and the other improvements in and about such buildings to a complete
architectural whole and to a functional condition. In the event of damage or
destruction which cannot reasonably be repaired within one (1) year (or, in the
case of an occurrence during the last year of the term of this Lease, within a
period of sixty (60) days) following the date of the occurrence, then either
Landlord or Tenant, at its election, may terminate this Lease as of the date of
the occurrence by giving written notice to the other within thirty (30) days
after the date of the occurrence; if neither party timely elects such
termination, then this Lease shall continue in full force and effect and
Landlord and Tenant shall each repair and restore applicable portions of the
Premises and the Center in accordance with the first sentence of this Section
15.1.

            (b) The respective obligations of Landlord and Tenant pursuant to
Section 15.1(a) are subject to the following limitations:

                  (i) If the occurrence results from a peril which is required
to be insured pursuant to Sections 12.1(c), (d) and (e) above, then Landlord and
Tenant shall use their

                                     - 27 -

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respective best efforts and cooperate diligently, reasonably and in good faith
to recover any available proceeds from the respective insurance which they are
required to maintain pursuant to Sections 12.1(c), (d) and/or (e), as
applicable, and to divide or allocate such proceeds between themselves in
accordance with their respective rebuilding obligations under Section 15.1(a),
and the obligations of each party shall not exceed its respective share of the
amount of insurance proceeds received from insurers (or, in the case of any
failure to maintain required insurance, proceeds that reasonably would have been
available if the required insurance had been maintained) by reason of such
occurrence, plus the amount of any deductible under the applicable insurance,
and, if such proceeds (including, in the case of a failure to maintain required
insurance, any proceeds that reasonably would have been available) are
insufficient, either party may terminate the Lease unless the other party
promptly elects and agrees, in writing, to contribute the amount of the
shortfall; and

                  (ii) If the occurrence results from a peril which is not
required to be insured pursuant to Sections 12.1(c), (d) and (e) above and is
not actually insured, Landlord shall be required to repair and restore the cold
shells of the applicable buildings and the Common Areas to the extent necessary
for Tenant's continued use and occupancy of the Premises, and Tenant shall be
required to repair and restore the other improvements in and about the Premises
to the extent necessary for Tenant's continued use and occupancy of the
Premises, provided that each party's obligation to repair and restore shall not
exceed an amount equal to five percent (5%) of the replacement cost of the cold
shells of the applicable buildings and the Common Area improvements, as to
Landlord, or five percent (5%) of the replacement cost of the other improvements
in and about the Premises, as to Tenant; if the replacement cost as to either
party exceeds such amount, then the party whose limit has been exceeded may
terminate this Lease unless the other party promptly elects and agrees, in
writing, to contribute the amount of the shortfall.

            (c) If this Lease is terminated pursuant to the foregoing provisions
of this Section 15.1 following an occurrence which is a peril actually insured
or required to be insured against pursuant to Sections 12.1(c), (d) and (e),
Landlord and Tenant agree (and any Lender shall be asked to agree) that such
insurance proceeds shall be allocated between Landlord and Tenant in a manner
which fairly and reasonably reflects their respective ownership rights under
this Lease, as of the termination or expiration of the term of this Lease, with
respect to the improvements, fixtures, equipment and other items to which such
insurance proceeds are attributable.

            (d) From and after the date of an occurrence resulting in damage to
or destruction of the Premises or of the Common Areas necessary for Tenant's use
and occupancy of the Premises, and continuing until repair and restoration
thereof are completed, there shall be an equitable abatement of minimum rental
and of Tenant's Operating Cost Share of Operating Expenses based upon the degree
to which Tenant's ability to conduct its business in the Premises is impaired.

      15.2  Condemnation.

            (a) If during the term of this Lease the Premises or the Common
Areas of the Center, or any substantial part of either, is taken by eminent
domain or by reason of any public improvement or condemnation proceeding, or in
any manner by exercise of the right of eminent domain (including any transfer in
avoidance of an exercise of the power of eminent domain), or receives
irreparable damage by reason of anything lawfully done under color of public or
other authority, then (i) this Lease shall terminate as to the entire Premises
at Landlord's election by written notice given to Tenant within sixty (60) days
after the taking has occurred, and (ii) this Lease shall terminate as to the
entire Premises at Tenant's election, by written notice given to Landlord within
thirty (30) days after the nature and extent of the taking have been finally
determined, if the portion of the Premises taken is of such extent and nature as
substantially to handicap, impede or permanently impair Tenant's use of the
balance of the Premises. If Tenant elects to terminate this Lease, Tenant shall
also notify Landlord of the date of termination, which date shall not be earlier
than thirty (30) days nor later than ninety (90) days after Tenant has

                                     - 28 -

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notified Landlord of Tenant's election to terminate, except that this Lease
shall terminate on the date of taking if such date falls on any date before the
date of termination designated by Tenant. If neither party elects to terminate
this Lease as hereinabove provided, this Lease shall continue in full force and
effect (except that there shall be an equitable abatement of minimum rental and
of Tenant's Operating Cost Share of Operating Expenses based upon the degree to
which Tenant's ability to conduct its business in the Premises is impaired),
Landlord shall restore the shell of the buildings in which the Premises are
located and Common Area improvements to a complete architectural whole and a
functional condition and as nearly as reasonably possible to the condition
existing before the taking, and Tenant shall restore the other improvements in
the Premises and Tenant's other alterations, additions and improvements to a
complete architectural whole and a functional condition and as nearly as
reasonably possible to the condition existing before the taking. In connection
with any such restoration, each party shall use its respective best efforts
(including, without limitation, any necessary negotiation or intercession with
its respective lender, if any) to ensure that any severance damages or other
condemnation awards intended to provide compensation for rebuilding or
restoration costs are promptly collected and made available to Landlord and
Tenant in portions reasonably corresponding to the cost and scope of their
respective restoration obligations, subject only to such payment controls as
either party or its lender may reasonably require in order to ensure the proper
application of such proceeds toward the restoration of the Improvements. Each
party waives the provisions of Code of Civil Procedure Section 1265.130,
allowing either party to petition the Superior Court to terminate this Lease in
the event of a partial condemnation of the Premises or the Center.

            (b) The respective obligations of Landlord and Tenant pursuant to
Section 15.2(a) are subject to the following limitations:

                  (i) Each party's obligation to repair and restore shall not
exceed, net of any condemnation awards or other proceeds available for and
allocable to such restoration as contemplated in Section 15.2(a), an amount
equal to five percent (5%) of the replacement cost of the shell of the buildings
in which the Premises are located and the Common Area improvements, as to
Landlord, or five percent (5%) of the replacement cost of the other improvements
in the Premises as to Tenant; if the replacement cost as to either party exceeds
such amount, then the party whose limit has been exceeded may terminate this
Lease unless the other party promptly elects and agrees, in writing, to
contribute the amount of the shortfall; and

                  (ii) If this Lease is terminated pursuant to the foregoing
provisions of this Section 15.2, or if this Lease remains in effect but any
condemnation awards or other proceeds become available as compensation for the
loss or destruction of any of the Improvements, then Landlord and Tenant agree
(and any Lender shall be asked to agree) that such proceeds shall be allocated
between Landlord and Tenant, respectively, in the respective proportions in
which Landlord and Tenant would have shared, under Section 15.1(c), the proceeds
of any insurance proceeds following loss or destruction of the applicable
Improvements by an insured casualty.

      15.3  Reservation Of Compensation. Landlord reserves, and Tenant waives
and assigns to Landlord, all rights to any award or compensation for damage to
the Premises, the Improvements, the Center and the leasehold estate created
hereby, accruing by reason of any taking in any public improvement, condemnation
or eminent domain proceeding or in any other manner by exercise of the right of
eminent domain or of anything lawfully done by public authority, except that (a)
Tenant shall be entitled to any and all compensation or damages paid for or on
account of Tenant's moving expenses, trade fixtures and equipment and any
leasehold improvements installed by Tenant in the Premises at its own sole
expense, but only to the extent Tenant would have been entitled to remove such
items at the expiration of the term of this Lease and then only to the extent
such compensation or damages are expressly and specifically allocated by the
condemning authority, in response to a direct claim by Tenant, to Tenant's
moving expenses, trade fixtures, equipment and/or removable leasehold
improvements as set forth in this clause (a), and (b) any condemnation awards or
proceeds described in Section 15.2(b)(ii) shall be allocated and disbursed in
accordance with the provisions of Section 15.2(b)(ii). notwithstanding any
contrary provisions of this Section 15.3.

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      15.4  Restoration Of improvements. In connection with any repair or
restoration of the Premises or other Improvements by either party following a
casualty or taking as hereinabove set forth, the party responsible for such
repair or restoration shall, to the extent possible, return such Improvements to
a condition substantially equal to that which existed immediately prior to the
casualty or taking. To the extent such party wishes to make material
modifications to the Premises or to such Improvements, such modifications shall
be subject to the prior written approval of the other party (not to be
unreasonably withheld or delayed), except that no such " approval shall be
required for modifications that are required by applicable governmental
authorities as a condition of the repair or restoration, unless such required
modifications would impair or impede Tenant's conduct of its business in the
Premises (in which case any such modifications in Landlord's work shall require
Tenant's consent, not unreasonably withheld or delayed) or would materially and
adversely affect the exterior appearance, the structural integrity or the
mechanical or other operating systems of the buildings in which the Premises are
located (in which case any such modifications in Tenant's work shall require
Landlord's consent, not unreasonably withheld or delayed).

                                   16. DEFAULT

      16.1  Events Of Default. The occurrence of any of the following shall
constitute an event of default on the part of Tenant:

            (a) [Omitted.]

            (b) Nonpayment. Failure to pay, when due, any amount payable to
Landlord hereunder, such failure continuing for a period of five (5) business
days after written notice of such failure; provided, however, that any such
notice shall be in lieu of, and not in addition to, any notice required under
California Code of Civil Procedure Section 1161 et seq., as amended from time to
time;

            (c) Other Obligations. Failure to perform any obligation, agreement
or covenant under this Lease other than those matters specified in subsection
(b) hereof, such failure continuing for thirty (30) days after written notice of
such failure; provided, however, that if such failure is curable in nature but
cannot reasonably be cured within such 30-day period, then Tenant shall not be
in default if, and so long as. Tenant promptly (and in all events within such
30-day period) commences such cure and thereafter diligently pursues such cure
to completion; and provided further, however, that any such notice shall be in
lieu of, and not in addition to, any notice required under California Code of
Civil Procedure Section 1161 et seq., as amended from time to time;

            (d) General Assignment. A general assignment by Tenant for the
benefit of creditors;

            (e) Bankruptcy. The filing of any voluntary petition in bankruptcy
by Tenant, or the filing of an involuntary petition by Tenant's creditors, which
involuntary petition remains undischarged for a period of thirty (30) days. In
the event that under applicable law the trustee in bankruptcy or Tenant has the
right to affirm this Lease and continue to perform the obligations of Tenant
hereunder, such trustee or Tenant shall, in such time period as may be permitted
by the bankruptcy court having jurisdiction, cure all defaults of Tenant
hereunder outstanding as of the date of the affirmance of this Lease and provide
to Landlord such adequate assurances as may be necessary to ensure Landlord of
the continued performance of Tenant's obligations under this Lease.
Specifically, but without limiting the generality of the foregoing, such
adequate assurances must include assurances that the Premises continue to be
operated only for the use permitted hereunder. The provisions hereof are to
assure that the basic understandings between Landlord and Tenant with respect to
Tenant's use of the Premises and the Common Areas and the benefits to Landlord
therefrom are preserved, consistent with the purpose and intent of applicable
bankruptcy laws;

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            (f) Receivership. The employment of a receiver appointed by court
order to take possession of substantially all of Tenant's assets or the
Premises, if such receivership remains undissolved for a period of thirty (30)
days;

            (g) Attachment. The attachment, execution or other judicial seizure
of all or substantially all of Tenant's assets or the Premises, if such
attachment or other seizure remains undismissed or undischarged for a period of
thirty (30) days after the levy thereof; or

            (h) Insolvency. The admission by Tenant in writing of its inability
to pay its debts as they become due, the filing by Tenant of a petition seeking
any reorganization or arrangement, composition, readjustment, liquidation,
dissolution or similar relief under any present or future statute, law or
regulation, the filing by Tenant of an answer admitting or failing timely to
contest a material allegation of a petition filed against Tenant in any such
proceeding or, if within thirty (30) days after the commencement of any
proceeding against Tenant seeking any reorganization or arrangement,
composition, readjustment, liquidation, dissolution or similar relief under any
present or future statute, law or regulation, such proceeding shall not have
been dismissed.

      16.2  Remedies Upon Tenant's Default.

            (a) Upon the occurrence of any event of default described in Section
16.1 hereof, Landlord, in addition to and without prejudice to any other rights
or remedies it may have, shall have the immediate right to re-enter the Premises
or any part thereof and repossess the same, expelling and removing therefrom all
persons and property (which property may be stored in a public warehouse or
elsewhere at the cost and risk of and for the account of Tenant), using such
force as may be necessary to do so (as to which Tenant hereby waives any claim
for loss or damage that may thereby occur). In addition to or in lieu of such
re-entry, and without prejudice to any other rights or remedies it may have,
Landlord shall have the right either (i) to terminate this Lease and recover
from Tenant all damages incurred by Landlord as a result of Tenant's default, as
hereinafter provided, or (ii) to continue this Lease in effect and recover rent
and other charges and amounts as they become due.

            (b) Even if Tenant has breached this Lease and abandoned the
Premises, this Lease shall continue in effect for so long as Landlord does not
terminate Tenant's right to possession under subsection (a) hereof and Landlord
may enforce all of its rights and remedies under this Lease, including the right
to recover rent as it becomes due, and Landlord, without terminating this Lease,
may exercise all of the rights and remedies of a lessor under California Civil
Code Section 1951.4 (lessor may continue lease in effect after lessee's breach
and abandonment and recover rent as it becomes due, if lessee has right to
sublet or assign, subject only to reasonable limitations), or any successor Code
section. Acts of maintenance, preservation or efforts to relet the Premises or
the appointment of a receiver upon application of Landlord to protect Landlord's
interests under this Lease shall not constitute a termination of Tenant's right
to possession.

            (c) If Landlord terminates this Lease pursuant to this Section 16.2,
Landlord shall have all of the rights and remedies of a landlord provided by
Section 1951.2 of the Civil Code of the State of California, or any successor
Code section, which remedies include Landlord's right to recover from Tenant (i)
the worth at the time of award of the unpaid rent and additional rent which had
been earned at the time of termination, (ii) the worth at the time of award of
the amount by which the unpaid rent and additional rent which would have been
earned after termination until the time of award exceeds the amount of such
rental loss that Tenant proves could have been reasonably avoided, (iii) the
worth at the time of award of the amount by which the unpaid rent and additional
rent for the balance of the term after the time of award exceeds the amount of
such rental loss that Tenant proves could be reasonably avoided, and (iv) any
other amount necessary to compensate Landlord for all the detriment proximately
caused by Tenant's failure to perform its obligations under this Lease or which
in the ordinary course of things would be likely to result  therefrom,
including, but not limited to, the cost of recovering possession of the
Premises, expenses of reletting, including necessary repair, renovation and

                                     - 31 -

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alteration of the Premises, reasonable attorneys' fees, and other reasonable
costs. The "worth at the time of award" of the amounts referred to in clauses
(i) and (ii) above shall be computed by allowing interest at ten percent (10%)
per annum from the date such amounts accrued to Landlord. The "worth at the time
of award" of the amounts referred to in clause (iii) above shall be computed by
discounting such amount at one percentage point above the discount rate of the
Federal Reserve Bank of San Francisco at the time of award.

      16.3  Remedies Cumulative. All rights, privileges and elections or
remedies of Landlord contained in this Article 16 are cumulative and not
alternative to the extent permitted by law and except as otherwise provided
herein.

                     17. SUBORDINATION, ATTORNMENT AND SALE

      17.1  Subordination To Mortgage. This Lease, and any sublease entered into
by Tenant under the provisions of this Lease, shall be subject and subordinate
to any ground lease, mortgage, deed of trust, sale/leaseback transaction or any
other hypothecation for security now or hereafter placed upon any portion(s) of
the Center on which the Premise are located, and to the rights of any assignee
of Landlord or of any ground lessor, mortgagee, trustee, beneficiary or
leaseback lessor under any of the foregoing, and to any and all advances made on
the security thereof and to all renewals, modifications, consolidations,
replacements and extensions thereof; provided, however, that such subordination
in the case of any future ground lease, mortgage, deed of trust, sale/leaseback
transaction or any other hypothecation for security placed upon any portion(s)
of the Center on which the Premises are located shall be conditioned on Tenant's
receipt from the ground lessor, mortgagee, trustee, beneficiary or leaseback
lessor of a Non-Disturbance Agreement in a form reasonably acceptable to Tenant
(i) confirming that so long as Tenant is not in material default hereunder
beyond any applicable cure period (for which purpose the occurrence of any event
of default under Section 16.1 hereof shall be deemed to be "material"), Tenant's
rights hereunder shall not be disturbed by such person or entity and (ii)
agreeing that the benefit of such Non-Disturbance Agreement shall be
transferable to any transferee under a Permitted Transfer and to any other
assignee or subtenant that is acceptable to the ground lessor, mortgagee,
trustee, beneficiary or leaseback lessor at the time of transfer. Moreover,
Tenant's obligations under this Lease shall be conditioned on Tenant's receipt,
within sixty (60) days after the date hereof (provided that Landlord shall have
the right to extend such period for up to an additional thirty (30) days in
order to continue pursuing receipt of the agreement required hereunder if not
received within such initial 60-day period), from The Northwestern Mutual Life
Insurance Company, the beneficiary under an existing deed of trust on the Phase
1 Property, of a Non-Disturbance Agreement in a form reasonably acceptable to
Tenant acknowledging and approving this Lease and confirming (i) that so long as
Tenant is not in material default hereunder beyond any applicable cure period
(for which purpose the occurrence of any event of default under Section 16.1
hereof shall be deemed to be "material")., Tenant's rights hereunder shall not
be disturbed by such person or entity and (ii) agreeing that the benefit of such
Non-Disturbance Agreement shall be transferable to any transferee under a
Permitted Transfer and to any other assignee or subtenant that is acceptable to
the ground lessor, mortgagee, trustee, beneficiary or leaseback lessor at the
time of transfer. If any mortgagee, trustee, beneficiary, ground lessor,
sale/leaseback lessor or assignee elects to have this Lease be an encumbrance
prior to the lien of its mortgage, deed of trust, ground lease or leaseback
lease or other security arrangement upon any portion(s) of the Center on which
the Premises are located and gives notice thereof to Tenant, this Lease shall be
deemed prior thereto, whether this Lease is dated prior or subsequent to the
date thereof or the date of recording thereof. Tenant, and any sublessee, shall
execute such documents as may reasonably be requested by any mortgagee, trustee,
beneficiary, ground lessor, sale/leaseback lessor or assignee to evidence the
subordination herein set forth, subject to the conditions set forth above, or to
make this Lease prior to the lien of any mortgage, deed of trust, ground lease,
leaseback lease or other security arrangement, as the case may be. Upon any
default by Landlord in the performance of its obligations under any mortgage,
deed of trust, ground lease, leaseback lease or assignment, Tenant (and any
sublessee) shall, notwithstanding any subordination hereunder, attorn to the
mortgagee, trustee, beneficiary, ground lessor, leaseback lessor or assignee
thereunder upon

                                     - 32 -

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demand and become the tenant of the successor in interest to Landlord, at the
option of such successor in interest, and shall execute and deliver any
instrument or instruments confirming the attornment herein provided for.

      17.2  Sale Of Landlord's Interest. Upon sale, transfer or assignment of
Landlord's entire interest in the portion(s) of the Center on which the Premises
are located. Landlord shall be relieved of its obligations hereunder with
respect to liabilities accruing from and after the date of such sale, transfer
or assignment.

      17.3  Estoppel Certificates. Tenant or Landlord (the "responding party"),
as applicable, shall at any time and from time to time, within ten (10) days
after written request by the other party (the "requesting party"), execute,
acknowledge and deliver to the requesting party a certificate in writing
stating: (i) that this Lease is unmodified and in full force and effect, or if
there have been any modifications, that this Lease is in full force and effect
as modified and stating the date and the nature of each modification; (ii) the
date to which rental and all other sums payable hereunder have been paid; (iii)
that the requesting party is not in default in the performance of any of its
obligations under this Lease, that the certifying party has given no notice of
default to the requesting party and that no event has occurred which, but for
the expiration of the applicable time period, would constitute an event of
default hereunder, or if the responding party alleges that any such default,
notice or event has occurred, specifying the same in reasonable detail; and (iv)
such other matters as may reasonably be requested by the requesting party or by
any institutional lender, mortgagee, trustee, beneficiary, ground lessor, sale/
leaseback lessor or prospective purchaser of any portion(s) of the Center on
which the Premises are located, or any prospective sublessee or assignee of this
Lease. Any such certificate provided under this Section 17.3 may be relied upon
by any lender, mortgagee, trustee, beneficiary, assignee or successor in
interest to the requesting party, by any prospective purchaser, by any purchaser
on foreclosure or sale, by any grantee under a deed in lieu of foreclosure of
any mortgage or deed of trust on the Center (or any portion thereof), by any
subtenant or assignee, or by any other third party. Failure to execute and
return within the required time any estoppel certificate requested hereunder, if
such failure continues for five (5) days after a second written request by the
requesting party for such estoppel certificate, shall be deemed to be an
admission of the truth of the matters set forth in the form of certificate
submitted to the responding party for execution.

      17.4  Subordination to CC&R's. This Lease, and any permitted sublease
entered into by Tenant under the provisions of this Lease, and the interests in
real property conveyed hereby and thereby shall be subject and subordinate to
any declarations of covenants, conditions and restrictions affecting the Center
(or any portion thereof) from time to time, provided that the terms of such
declarations are reasonable, do not materially impair Tenant's ability to
conduct the uses permitted hereunder on the Premises and in the Center, and do
not discriminate against Tenant relative to other similarly situated tenants
occupying the portion(s) of the Center covered by such declaration(s). Moreover,
this Lease, and any permitted sublease entered into by Tenant under the
provisions of this Lease, and the interests in real property conveyed hereby and
thereby shall also be subject and subordinate (a) to the Declaration of
Covenants, Conditions and Restrictions for Pointe Grand Business Park dated
November 4, 1991 and recorded on February 25, 1992 as Instrument No. 92025214,
Official Records of San Mateo County, as amended from time to time (the "Master
Declaration"), the provisions of which Master Declaration are an integral part
of this Lease to the extent this sentence is applicable, (b) to the Declaration
of Covenants, Conditions and Restrictions dated November 23, 1987 and recorded
on November 24, 1987 as Instrument No. 87177987, Official Records of San Mateo
County, which declaration imposes certain covenants, conditions and restrictions
on the Pointe Grand Business Park, and (c) to the Environmental Restriction and
Covenant (Pointe Grand) dated as of April 16, 1997 and recorded on April 16,
1997 as Instrument No. 97-043682, Official Records of San Mateo County, which
declaration imposes certain covenants, conditions and restrictions on the Pointe
Grand Business Park. Tenant agrees to execute, upon request by Landlord, any
documents reasonably required from time to time to evidence such subordination.

      17.5  Mortgagee Protection. If, following a default by Landlord under any
mortgage, deed of trust, ground lease, leaseback lease or other security
arrangement covering any portion(s)

                                     - 33 -

<PAGE>

of the Center on which the Premises are located, any such portion(s) of the
Center are acquired by the mortgagee, beneficiary, master lessor or other
secured party, or by any other successor owner, pursuant to a foreclosure,
trustee's sale, sheriff's sale, lease termination or other similar procedure (or
deed in lieu thereof), then any such person or entity so acquiring any
portion(s) of the Center on which the Premises are located shall not be:

            (a) liable for any act or omission of a prior landlord or owner of
such portion(s) of the Center (including, but not limited to, Landlord);

            (b) subject to any offsets or defenses that Tenant may have against
any prior landlord or owner of such portion(s) of the Center (including, but not
limited to, Landlord);

            (c) bound by any rent or additional rent that Tenant may have paid
in advance to any prior landlord or owner of such portion(s) of the Center
(including, but not limited to, Landlord) for a period in excess of one month,
or by any security deposit, cleaning deposit or other prepaid charge that Tenant
may have paid in advance to any prior landlord or owner (including, but not
limited to, Landlord), except to the extent such deposit or prepaid amount has
been expressly turned over to or credited to the successor owner thus acquiring
such portion(s) of the Center;

            (d) liable for any warranties or representations of any nature
whatsoever, whether pursuant to this Lease or otherwise, by any prior landlord
or owner of such portion(s) of the Center (including, but not limited to,
Landlord) with respect to the use, construction, zoning, compliance with laws,
title, habitability, fitness for purpose or possession, or physical condition
(including, without limitation, environmental matters) of the Center or any
portion thereof; or

            (e) liable to Tenant in any amount beyond the interest of such
mortgagee, beneficiary, master lessor or other secured party or successor owner
in such portion(s) of the Center, it being the intent of this provision that
Tenant shall look solely to the interest of any such mortgagee, beneficiary,
master lessor or other secured party or successor owner in such portion(s) of
the Center for the payment and discharge of the landlord's obligations under
this Lease and that such mortgagee, beneficiary, master lessor or other secured
party or successor owner shall have no separate personal liability for any such
obligations.

                                  18. SECURITY

      18.1  Deposit. Tenant is not required to provide any security deposit to
Landlord pursuant to this Lease.

                                19. MISCELLANEOUS

      19.1  Notices. All notices, consents, waivers and other communications
which this Lease requires or permits either party to give to the other shall be
in writing and shall be deemed given when delivered personally (including
delivery by private courier or express delivery service) or four (4) days after
deposit in the United States mail, registered or certified mail, postage
prepaid, addressed to the parties at their respective addresses as follows:

        To Tenant:         COR Therapeutics, Inc.
                           256 East Grand Avenue
                           South San Francisco. CA 94080
                           Attn: Charles A. Alaimo

        with copy to:      Cooley Godward LLP
                           One Maritime Plaza, 20th Floor
                           San Francisco. CA 94111-3580
                           Attn: Anna B. Pope, Esq.

                                     - 34 -

<PAGE>

        To Landlord:       Britannia Pointe Grand Limited Partnership
                           1939 Harrison Street, Suite 715
                           Park Plaza Building
                           Oakland, CA 94612
                           Attn: T. J. Bristow

        with copy to:      Folger Levin & Kahn LLP
                           Embarcadero Center West
                           275 Battery Street, 23rd Floor
                           San Francisco, CA 94111
                           Attn: Donald E. Kelley,Jr.

        and copy to:       Slough Estates USA Inc.
                           33 West Monroe Street, Suite 2000
                           Chicago, IL 60603
                           Attn: Randy Rohner

or to such other address as may be contained in a notice at least fifteen (15)
days prior to the address change from either parry to the other given pursuant
to this Section. Rental payments and other sums required by this Lease to be
paid by Tenant shall be delivered to Landlord at Landlord's address provided in
this Section, or to such other address as Landlord may from time to time specify
in writing to Tenant, and shall be deemed to be paid only upon actual receipt.

      19.2  Successors And Assigns. The obligations of this Lease shall run with
the land, and this Lease shall be binding upon and inure to the benefit of the
parties hereto and their respective successors and assigns, except that the
original Landlord named herein and each successive Landlord under this Lease
shall be liable only for obligations accruing during the period of its ownership
of the portion(s) of the Center on which the Premises are located, and any
liability for obligations accruing after termination of such ownership shall
terminate as of the date of such termination of ownership and shall pass to the
successor lessor.

      19.3  No Waiver. The failure of Landlord to seek redress for violation, or
to insist upon the strict performance, of any covenant or condition of this
Lease shall not be deemed a waiver of such violation, or prevent a subsequent
act which would originally have constituted a violation from having all the
force and effect of an original violation.

      19.4  Severability. If any provision of this Lease or the application
thereof is held to be invalid or unenforceable, the remainder of this Lease or
the application of such provision to persons or circumstances other than those
as to which it is invalid or unenforceable shall not be affected thereby, and
each of the provisions of this Lease shall be valid and enforceable, unless
enforcement of this Lease as so invalidated would be unreasonable or grossly
inequitable under all the circumstances or would materially frustrate the
purposes of this Lease.

      19.5  Litigation Between Parties. In the event of any litigation or other
dispute resolution proceedings between the panics hereto arising out of or in
connection with this Lease, the prevailing party shall be reimbursed for all
reasonable costs, including, but not limited to, reasonable accountants' fees
and attorneys' fees, incurred in connection with such proceedings (including,
but not limited to, any appellate proceedings relating thereto) or in connection
with the enforcement of any judgment or award rendered in such proceedings.
"Prevailing party" within the meaning of this Section shall include, without
limitation, a party who dismisses an action for recovery hereunder in exchange
for payment of the sums allegedly due, performance of covenants allegedly
breached or consideration substantially equal to the relief sought in the
action.

      19.6  Surrender. A voluntary or other surrender of this Lease by Tenant,
or a mutual termination thereof between Landlord and Tenant, shall not result in
a merger but shall, at the option of Landlord, operate either as an assignment
to Landlord of any and all existing subleases

                                     - 35 -

<PAGE>

and subtenancies, or a termination of all or any existing subleases and
subtenancies. This provision shall be contained in any and all assignments or
subleases made pursuant to this Lease.

      19.7  Interpretation. The provisions of this Lease shall be construed as a
whole, according to their common meaning, and not strictly for or against
Landlord or Tenant. The captions preceding the text of each Section and
subsection hereof are included only for convenience of reference and shall be
disregarded in the construction or interpretation of this Lease.

      19.8  Entire Agreement. This written Lease, together with the exhibits
hereto, contains all the representations and the entire understanding between
the parties hereto with respect to the subject matter hereof. Any prior
correspondence, memoranda or agreements are replaced in total by this Lease and
the exhibits hereto. This Lease may be modified only by an agreement in writing
signed by each of the parties.

      19.9  Governing Law. This Lease and all exhibits hereto shall be construed
and interpreted in accordance with and be governed by all the provisions of the
laws of the State of California.

      19.10 No Partnership. The relationship between Landlord and Tenant is
solely that of a lessor and lessee. Nothing contained in this Lease shall be
construed as creating any type or manner of partnership, joint venture or joint
enterprise with or between Landlord and Tenant.

      19.11 Financial Information. From time to time Tenant shall promptly
provide directly to prospective lenders and purchasers of the portion(s) of the
Center on which the Premises are located, as designated by Landlord from time to
time, such financial information pertaining to the financial status of Tenant as
Landlord may reasonably request; provided, Tenant shall be permitted to provide
such financial information in a manner which Tenant deems reasonably necessary
to protect the confidentiality of such information. In addition, from time to
time, Tenant shall provide Landlord with such financial information pertaining
to the financial status of Tenant as Landlord may reasonably request. Landlord
agrees that all financial information supplied to Landlord by Tenant shall be
treated as confidential material, and shall not be disseminated to any party or
entity (including any entity affiliated with Landlord) without Tenant's prior
written consent, except that Landlord shall be entitled to provide such
information, subject to reasonable precautions to protect the confidential
nature thereof, (i) to Landlord's partners and professional advisors, solely to
use in connection with Landlord's execution and enforcement of this Lease, and
(ii) to prospective lenders and/or purchasers of the portion(s) of the Center
on which the Premises are located, solely for use in connection with their bona
fide consideration of a proposed financing or purchase of the portion(s) of the
Center on which the Premises are located, provided that such prospective lenders
and/or purchasers are not then engaged in businesses directly competitive with
the business then being conducted by Tenant. For purposes of this Section,
without limiting the generality of the obligations provided herein, it shall be
deemed reasonable for Landlord to request copies of Tenant's most recent audited
annual financial statements, or, if audited statements have not been prepared,
unaudited financial statements for Tenant's most recent fiscal year, accompanied
by a certificate of Tenant's chief financial officer that such financial
statements fairly present Tenant's financial condition as of the date(s)
indicated. Notwithstanding any other provisions of this Section 19.11, during
any period in which Tenant has outstanding a class of publicly traded securities
and is filing with the Securities and Exchange Commission, on a regular basis,
Forms 10Q and 10K and any other periodic filings required under the Securities
Exchange Act of 1934, as amended, it shall constitute sufficient compliance
under this Section 19.11 for Tenant to furnish Landlord with copies of such
periodic filings upon Landlord's written request.

            Landlord and Tenant recognize the need of Tenant to maintain the
confidentiality of information regarding its financial status and the need of
Landlord to be informed of, and to provide to prospective lenders and purchasers
of the portion(s) of the Center on which the Premises are located, financial
information pertaining to, Tenant's financial status. Landlord and

                                     - 36 -

<PAGE>

Tenant agree to cooperate with each other in achieving these needs within the
context of the obligations set forth in this Section.

      19.12 Costs. If Tenant requests the consent of Landlord under any
provision of this Lease for any act that Tenant proposes to do hereunder,
including, without limitation, assignment of this Lease or subletting of the
Premises or any portion thereof, Tenant shall, as a condition to doing any such
act and the receipt of such consent, reimburse Landlord promptly for any and all
reasonable costs and expenses incurred by Landlord in connection therewith,
including, without limitation, reasonable attorneys' fees, up to a maximum of
$2,500.00 per request.

      19.13 Time. Time is of the essence of this Lease, and of every term and
condition hereof.

      19.14 Rules And Regulations. Tenant shall observe, comply with and obey,
and shall cause its employees, agents and, to the best of Tenant's ability,
invitees to observe, comply with and obey such rules and regulations as Landlord
may reasonably promulgate from time to time for the safety, care, cleanliness,
order and use of the Improvements, the Premises and the Center.

      19.15 Brokers. Landlord agrees to pay a fee of $300,000 to Tenant's
consultant. CB Richard Ellis (attn: Chris Jacobs), in connection with the
consummation of this Lease in accordance with a separate agreement. Such fee
shall be due and payable in full on or before September 15, 2001. Each party
represents and warrants that no other broker participated in the consummation
of this Lease and agrees to indemnify, defend and hold the other party harmless
against any liability, cost or expense, including, without limitation,
reasonable attorneys' fees, arising out of any claims for brokerage commissions
or other similar compensation in connection with any conversations, prior
negotiations or other dealings by the indemnifying party with any other broker.

      19.16 Memorandum Of Lease. At any time during the term of this Lease,
either party, at its sole expense, shall be entitled to record a memorandum of
this Lease and, if either party so elects, both parties agree to cooperate in
the preparation, execution, acknowledgement and recordation of such document in
reasonable form.

      19.17 Corporate Authority. Each of the persons signing this Lease on
behalf of Tenant warrants that he or she is fully authorized to do so and, by
jointly so signing, to bind Tenant.

      19.18 Execution and Delivery. This Lease may be executed in one or more
counterparts and by separate panics on separate counterparts, but each such
counterpart shall constitute an original and all such counterparts together
shall constitute one and the same instrument.

      19.19 Survival. Without limiting survival provisions which would otherwise
be implied or construed under applicable law, the provisions of Sections
2.5, 7.4, 9.2, 9.3, 9.4, 11.6, 12.6 and 19.5 hereof shall survive the
termination of this Lease with respect to matters occurring prior to the
expiration of this Lease.

      19.20 Parking. Landlord and Tenant agree that the Common Areas, taken as a
whole, shall include parking in amounts sufficient to satisfy the minimum
parking requirements of the City of South San Francisco applicable to the Center
from time to time.

                     [rest of page intentionally left blank]

                                     - 37 -

<PAGE>

      IN WITNESS WHEREOF, the parties hereto have executed this Lease as of the
day and year first set forth above.

          "Landlord"                                   "Tenant"

BRITANNIA POINTE GRAND LIMITED                COR THERAPEUTICS, INC. a Delaware
PARTNERSHIP, a Delaware limited               corporation
partnership

By: BRITANNIA POINTE GRAND,                   By: /s/ [ILLEGIBLE]
    LLC, a California limited liability           --------------------
    company, General Partner                  Its: [ILLEGIBLE]

By: /s/ T. J. Bristow                         By: /s/ [ILLEGIBLE]
    ------------------------                      -------------------------
    T. J. Bristow                             Its:
    Its Manager, President and                    -------------------------
    Chief Financial Officer

                                     - 38 -

<PAGE>

                                    EXHIBITS

 EXHIBIT A          Real Property Description

 EXHIBIT A-1        Phase I Property (Plan)

 EXHIBIT B          Site Plan

 EXHIBIT C          Future Entrance Lobby

<PAGE>

                                    EXHIBIT A

                           REAL PROPERTY DESCRIPTION

The Phase I Property:

All that certain real property in the City of South San Francisco, County of San
Mateo. State of California, more particularly described as follows:

Lot 3 as shown on Parcel Map No. 91-284, "Being a resubdivision of the parcels
described in the deeds to Metal and Thermit Corporation, recorded in Book 293,
at Page 394 of Deeds; in Book 49, at Page 490, Official Records; in Book 77, at
Page 415, Official Records; and, except that parcel described in Book 1352, at
Page 373, Official Records," filed on February 25, 1992, in Book 65 of Parcel
Maps, in the Office of the Recorder of the County of San Mateo, California.

The Center:

All that certain real property in the City of South San Francisco, County of San
Mateo. State of California, more particularly described as follows:

Lots 1,2,3 and 4, inclusive, as shown on Parcel Map No. 91-284, "Being a
resubdivision of the parcels described in the deeds to Metal and Thermit
Corporation, recorded in Book 293. at Page 394 of Deeds; in Book 49, at Page
490, Official Records; in Book 77. at Page 415. Official Records; and, except
that parcel described in Book 1352, at Page 373, Official Records." filed on
February 25,1992, in Book 65 of Parcel Maps, in the Office of the Recorder of
the County of San Mateo, California.

Together with all adjacent or substantially adjacent areas owned by Landlord and
depicted on the Site Plan (Exhibit B to this Lease) as being part of the Center.

                                   EXHIBIT A

<PAGE>
                                  EXHIBIT A-1

                            PHASE I PROPERTY (PLAN)

                                     [MAP]

<PAGE>
                                   EXHIBIT B

                                   SITE PLAN

                                     [MAP]

<PAGE>
                                   EXHIBIT C

                             FUTURE ENTRANCE LOBBY

                                     [MAP]

<PAGE>

                                     [MAP]

<PAGE>

                                     [MAP]

<PAGE>

                                   EXHIBIT B

                 [LAYOUT OF PREMISES SUBLEASED TO BE ATTACHED]

                                      12.
<PAGE>

                                  [FLOOR PLAN]

<PAGE>

                                  [FLOOR PLAN]
<PAGE>

                                    EXHIBIT B

                  DEPICTION OF LICENSED PREMISES AND LAB SPACE

<PAGE>

270 EAST GRAND AVE
SUITE 22                [***] FACILITY
1ST FLOOR

                                     [MAP]

***  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>

270 EAST GRAND AVE
SUITE 22
2ND FLOOR

                                     [MAP]
                                     [***]

***  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>

                                    EXHIBIT C

                              RULES AND REGULATIONS

-     All [***] studies must be in accordance with Portola [***] and in
      compliance with [***] regulations for [***] and [***] of [***].

-     Cytokinetics shall not conduct any [***] experiment without obtaining
      prior written approval from Portola's [***] and [***], which approval
      shall not be unreasonably withheld.

-     Each and every Cytokinetics Personnel using the Licensed Premises and/or
      Portola resources shall behave in accordance with basic definitions of
      appropriate workplace conduct as promulgated by Portola.

-     Each Party accepts full responsibility for any inappropriate conduct or
      disruptive behavior by its employees. Unacceptable behavior involving
      actions, words, jokes, or comments based on an individual's gender, race,
      ethnicity, age, religion, sexual orientation, disability or any other such
      characteristic will not be tolerated and may be grounds for termination of
      the Agreement by either Party.

***  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>

                                    EXHIBIT D

                                   LICENSE FEE

LICENSE FEE:  THE LICENSE FEE SHALL BE EQUAL TO THE SUM OF:
     [***]% of the Space Costs for the Lab Space
     [***]% of the Space Costs for the Exclusive Space
     [***]% of General Lab Operating Costs (excluding Direct Cytokinetics Costs)
     [***]% of the General [***] Purchases
     [***]% of Support Costs
     [***]% of [***] Costs (excluding Direct Cytokinetics Costs)
     [***]% of Maintenance and Administration Costs
     and [***]% of Additional Costs

as more fully described in the tables below.

[***]

*** 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>

                                    EXHIBIT E

                                  RESEARCH PLAN

1.    Portola will conduct [***] activities for Cytokinetics in support of [***]
      studies for the Cytokinetics Research and Development Programs in the
      following [***] (as determined by the Research Committee): [***], [***],
      [***] and [***]. Study [***] will be [***]using [***], [***], [***] or
      [***] of [***] and [***] will be obtained and provided to Cytokinetics for
      further analysis.

2.    Portola and Cytokinetics will work collaboratively on [***], [***], and
      [***] associated with products being developed under the Cytokinetics
      Research and Development Programs. The Research Committee will determine
      the amount and timing of Portola's work in this area, which will depend on
      specific program needs, but in any event Portola's efforts will normally
      be limited to [***] ([***]) FTEs at any given time.

3.    Cytokinetics and Portola will work together to expand the range of
      collaborative studies related to the Cytokinetics Research and Development
      Programs and in line with Portola's expertise. These studies may include:

            a. [***] and [***] studies using [***] and [***].

            b. [***]/[***] studies with [***] compounds.

            c. [***]studies in [***] in [***].

            d. [***] studies.

            e. [***] studies in [***].

            f. [***] studies in [***].

            g. [***]/[***] and [***] in [***].

            h. [***] studies.

            i. General [***], [***] and/or [***] as required and deemed
               appropriate by the Research Committee.

            j. [***] relating to [***].

*** 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>

                                    EXHIBIT F

                          PERMITTED HAZARDOUS MATERIALS

[***]

*** 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>

                                    EXHIBIT G

                           PORTOLA HAZARDOUS MATERIALS

                                    [***]

***  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>

                                    EXHIBIT H

                             CYTOKINETICS EQUIPMENT

<TABLE>
<CAPTION>
                              CYTOKINETICS
EQUIPMENT       DESCRIPTION      ASSET #
<S>             <C>           <C>
[***]
</TABLE>

*** 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>
                                                                     PAGE
<S>                                                                  <C>
1.  Definitions..................................................      1
2.  Collaboration................................................      5
3.  Licenses.....................................................      8
4.  License Fees and Costs.......................................     10
5.  Intellectual Property and Inventions.........................     12
6.  Cytokinetics Materials.......................................     13
7.  Confidentiality..............................................     14
8.  Compliance with Permits; Hazardous Materials.................     18
9.  Condition of Licensed Premises and Personal Property.........     19
10. Use/Allocation of Liability..................................     20
11. Insurance and Liability......................................     20
12. Indemnity....................................................     21
13. Term; Extension..............................................     22
14. Termination..................................................     22
15. General......................................................     23
</TABLE>

                                      -i-<PAGE>

                                                                   EXHIBIT 10.47

                           CYTOKINETICS, INCORPORATED

                         EXECUTIVE EMPLOYMENT AGREEMENT

      This Executive Employment Agreement (the "Agreement") is made and entered
into by and between Gail Sheridan (the "Executive") and Cytokinetics,
Incorporated, a Delaware Corporation (the "Company"), effective as of July 7,
2004 (the "Effective Date").

                                    RECITALS

WHEREAS: It is expected that the Company from time to time will consider the
possibility of an acquisition by another company or other change of control. The
Board of Directors of the Company (the "Board") recognizes that such
consideration can be a distraction to Executive and can cause Executive to
consider alternative employment opportunities. The Board has determined that it
is in the best interests of the Company and its stockholders to assure that the
Company will have the continued dedication and objectivity of Executive,
notwithstanding the possibility, threat or occurrence of a Change of Control of
the Company.

WHEREAS: The Board believes that it is in the best interests of the Company and
its stockholders to provide Executive with an incentive to continue his or her
employment and to motivate Executive to maximize the value of the Company upon a
Change of Control for the benefit of its stockholders.

WHEREAS: The Board believes that it is imperative to provide Executive with
certain severance benefits upon Executive's termination of employment following
a Change of Control. These benefits will provide Executive with enhanced
financial security and incentive and encouragement to remain with the Company
notwithstanding the possibility of a Change of Control.

WHEREAS: Certain capitalized terms used in the Agreement are defined in Section
11 below.

                                    AGREEMENT

      NOW, THEREFORE, in consideration of the mutual covenants contained herein,
the parties hereto agree as follows:

      1. Term of Agreement. This Agreement shall terminate upon the date that
all of the obligations of the parties hereto with respect to this Agreement have
been satisfied.

      2. At-Will Employment. The Company and Executive acknowledge that
Executive's employment is and shall continue to be at-will, as defined under
applicable law. If Executive's employment terminates for any reason, including
(without limitation) any termination prior to a Change of Control, Executive
shall not be entitled to any payments, benefits, damages, awards or compensation
other than as provided by this Agreement or by law.

      3. Duties and Scope of Employment.

            (a) Positions and Duties. As of the Effective Date, Executive will
serve as the Vice President, Human Resources of the Company. Executive will
render such business and professional

<PAGE>

services in the performance of his duties, consistent with Executive's position
within the Company, as will reasonably be assigned to him by the Company's Board
of Directors.

            (b) Obligations. During such time as the Executive is employed by
the Company, Executive will perform his duties faithfully and to the best of his
ability and will devote his full business efforts and time to the Company.
During such time as the Executive is employed by the Company, Executive agrees
not to actively engage in any other employment, occupation or consulting
activity for any material direct or indirect remuneration without the prior
approval of the Board.

      4. Compensation.

            (a) Base Salary. During such time as the Executive is employed by
the Company, the Company will pay Executive an annual salary as determined in
the discretion of the Board of Directors or any committee thereof. The base
salary will be paid periodically in accordance with the Company's normal payroll
practices and will be subject to the usual, required withholding. Executive's
salary will be subject to review and adjustments will be made based upon the
Company's normal performance review practices.

            (b) Performance Bonus. Executive will be eligible to receive an
annual bonus and other bonuses, less applicable withholding taxes, as determined
by the Board of Directors or any committee thereof in the Board's or such
committee's sole discretion.

            (c) Equity Compensation. Executive will be eligible to receive stock
and option grants, and other equity compensation awards, as determined by the
Board of Directors or any committee thereof in the Board's or such committee's
sole discretion.

      5. Employee Benefits. During the time that Executive is an employee of the
Company, Executive will be entitled to participate in the Benefit Plans
currently and hereafter maintained by the Company of general applicability to
other senior executives of the Company. The Company reserves the right to cancel
or change the Benefit Plans it offers to its employees at any time.

      6. Vacation. Executive will be entitled to vacation in accordance with the
Company's vacation policy, with the timing and duration of specific vacations
mutually and reasonably agreed to by the parties hereto.

      7. Expenses. The Company will reimburse Executive for reasonable travel,
entertainment or other expenses incurred by Executive in the furtherance of or
in connection with the performance of Executive's duties as an employee of the
Company, in accordance with the Company's expense reimbursement policy as in
effect from time to time.

      8. Severance Benefits.

            (a) Involuntary Termination Following a Change of Control. If within
eighteen (18) months following a Change of Control (X)(i) Executive terminates
his or her employment with the Company (or any parent or subsidiary of the
Company) for Good Reason or (ii) the Company (or any parent or subsidiary of the
Company) terminates Executive's employment for other than Cause, and (Y)
Executive signs and does not revoke a standard release of claims with the
Company in a

                                                                             -2-
<PAGE>

form reasonably acceptable to the Company, then Executive shall receive the
following severance from the Company:

                  (i) Severance Payment. Executive will be entitled to (i)
receive continuing payments of severance pay (less applicable withholding taxes)
at a rate equal to his base salary rate, as then in effect, for a period of
eighteen (18) months from the date of such termination, to be paid periodically
in accordance with the Company's normal payroll policies; and (B) a lump-sum
payment equal to 100% of Executive's target annual bonus as of the date of such
termination.

                  (ii) Options; Restricted Stock. All of Executive's then
outstanding options to purchase shares of the Company's Common Stock (the
"Options") shall immediately vest and become exercisable (that is, in addition
to the shares subject to the Options which have vested and become exercisable as
of the date of such termination), but in no event shall the number of shares
subject to such Options which so vest exceed the total number of shares subject
to such Options. Additionally, all of the shares of the Company's Common Stock
then held by Executive subject to a Company right of repurchase (the "Restricted
Stock") shall immediately vest and have such Company right of repurchase with
respect to such shares of Restricted Stock lapse (that is, in addition to the
shares of Restricted Stock which have vested as of the date of such
termination), but in no event shall the number of shares which so vest exceed
the number of shares of Restricted Stock outstanding immediately prior to such
termination.

                  (iii) Continued Employee Benefits. Executive shall receive
Company-paid coverage for Executive and Executive's eligible dependents under
the Company's Benefit Plans for a period equal to the shorter of (i) eighteen
(18) months or (ii) such time as Executive secures employment with benefits
generally similar to those provided in the Company's Benefit Plans.

            (b) Timing of Severance Payments. Any lump-sum severance payment to
which Executive is entitled shall be paid by the Company to Executive in cash
and in full, not later than ten (10) calendar days after the date of the
termination of Executive's employment as provided in Section 8(a), and any other
severance payments shall be paid in accordance with normal payroll policies as
provided in Section 8(a). If Executive should die before all amounts have been
paid, such unpaid amounts shall be paid in a lump-sum payment to Executive's
designated beneficiary, if living, or otherwise to the personal representative
of Executive's estate.

            (c) Voluntary Resignation; Termination for Cause. If Executive's
employment with the Company terminates (i) voluntarily by Executive other than
for Good Reason or (ii) for Cause by the Company, then Executive shall not be
entitled to receive severance or other benefits except for those as may then be
established under the Company's then existing severance and Benefits Plans or
pursuant to other written agreements with the Company.

            (d) Disability; Death. If the Company terminates Executive's
employment as a result of Executive's Disability, or Executive's employment
terminates due to his or her death, then Executive shall not be entitled to
receive severance or other benefits except for those as may then be established
under the Company's then existing written severance and Benefits Plans or
pursuant to other written agreements with the Company.

                                                                             -3-
<PAGE>

            (e) Termination Apart from Change of Control. In the event
Executive's employment is terminated for any reason, either prior to the
occurrence of a Change of Control or after the eighteen (18) month period
following a Change of Control, then Executive shall be entitled to receive
severance and any other benefits only as may then be established under the
Company's existing written severance and Benefits Plans, if any, or pursuant to
any other written agreements with the Company.

            (f) Exclusive Remedy. In the event of a termination of Executive's
employment within eighteen (18) months following a Change of Control, the
provisions of this Section 8 are intended to be and are exclusive and in lieu of
any other rights or remedies to which Executive or the Company may otherwise be
entitled, whether at law, tort or contract, in equity, or under this Agreement.
Executive shall be entitled to no benefits, compensation or other payments or
rights upon termination of employment following a Change in Control other than
those benefits expressly set forth in this Section 8.

      9. Conditional Nature of Severance Payments.

            (a) Proprietary Information and Invention Assignment Agreement. If
Executive is in material breach of the terms of the Proprietary Information and
Invention Assignment Agreement, by and between the Company and Executive, dated
as of December 26, 2003 (the "Invention Agreement"), including, without
limitation, Executive's obligations of confidentiality and of non-solicitation
contained in the Invention Agreement, then upon such breach by Executive: (i)
Executive shall refund to the Company all cash paid to Executive pursuant to
Section 8 of this Agreement; and (ii) all severance benefits pursuant to this
Agreement shall immediately cease.

            (b) Non-Competition. Executive acknowledges that the nature of the
Company's business is such that if Executive were to become employed by, or
substantially involved in, the business of a competitor of the Company during
the eighteen (18) months following the termination of Executive's employment
with the Company, it would be very difficult for Executive not to rely on or use
the Company's trade secrets and confidential information. Thus, to avoid the
inevitable disclosure of the Company's trade secrets and confidential
information, Executive agrees and acknowledges that Executive's right to receive
the severance payments set forth in this Agreement (to the extent Executive is
otherwise entitled to such payments) will be conditioned upon Executive not
directly or indirectly engaging in (whether as an employee, consultant, agent,
proprietor, principal, partner, stockholder, corporate officer, director or
otherwise), nor having any ownership interest in or participating in the
financing, operation, management or control of, any person, firm, corporation or
business that competes with the Company or is a customer of the Company.
Notwithstanding the foregoing, Executive may own, directly or indirectly, up to
1% of the capital stock of a company that competes with the Company, provided
such capital stock is traded on a national securities exchange or through the
automated quotation system of a registered securities association. Upon any
breach of this section, all severance payments pursuant to this Agreement will
immediately cease.

            (c) Understanding of Obligations. Executive represents that he is
fully aware of his obligations under the Invention Agreement and hereunder,
including, without limitation, the reasonableness of the length of time, scope
and geographic coverage of any such obligations.

                                                                             -4-
<PAGE>

      10. Limitation on Payments. In the event that the severance and other
benefits provided for in this Agreement or otherwise payable to Executive (i)
constitute "parachute payments" within the meaning of Section 280G of the
Internal Revenue Code of 1986, as amended (the "Code") and (ii) but for this
Section 10, would be subject to the excise tax imposed by Section 4999 of the
Code, then Executive's severance benefits shall be either:

            (a) delivered in full, or

            (b) delivered as to such lesser extent which would result in no
portion of such severance benefits being subject to excise tax under Section
4999 of the Code,

whichever of the foregoing amounts, taking into account the applicable federal,
state and local income taxes and the excise tax imposed by Section 4999, results
in the receipt by Executive on an after-tax basis, of the greatest amount of
severance benefits, notwithstanding that all or some portion of such severance
benefits may be taxable under Section 4999 of the Code. Unless the Company and
Executive otherwise agree in writing, any determination required under this
Section 10 shall be made in writing by the Company's independent public
accountants immediately prior to Change of Control (the "Accountants"), whose
determination shall be conclusive and binding upon Executive and the Company for
all purposes. For purposes of making the calculations required by this Section
10, the Accountants may make reasonable assumptions and approximations
concerning applicable taxes and may rely on reasonable, good faith
interpretations concerning the application of Sections 280G and 4999 of the
Code. The Company and Executive shall furnish to the Accountants such
information and documents as the Accountants may reasonably request in order to
make a determination under this Section. The Company shall bear all costs the
Accountants may reasonably incur in connection with any calculations
contemplated by this Section 10. If there is a reduction pursuant to this
Section 10 of the severance benefits to be delivered to Executive, such
reduction shall first be applied to any cash amounts to be delivered to the
Executive under this Agreement and thereafter to any other severance benefits of
Executive hereunder.

      11. Definition of Terms. The following terms referred to in this Agreement
shall have the following meanings:

            (a) Benefit Plans. "Benefit Plans" means plans, policies or
arrangements that the Company sponsors (or participates in) and that immediately
prior to Executive's termination of employment provide Executive and/or
Executive's eligible dependents with medical, dental, vision and/or financial
counseling benefits. Benefit Plans do not include any other type of benefit
(including, but not by way of limitation, disability, life insurance or
retirement benefits). A requirement that the Company provide Executive and
Executive's eligible dependents with coverage under the Benefit Plans will not
be satisfied unless the coverage is no less favorable than that provided to
Executive and Executive's eligible dependents immediately prior to Executive's
termination of employment. Notwithstanding any contrary provision of this
Section 11, but subject to the immediately preceding sentence, the Company may,
at its option, satisfy any requirement that the Company provide coverage under
any Benefit Plan by instead providing coverage under a separate plan or plans
providing coverage that is no less favorable or by paying Executive a lump-sum
payment sufficient to provide Executive and Executive's eligible dependents with
equivalent coverage under a third party plan that is reasonably available to
Executive and Executive's eligible dependents.

                                                                             -5-
<PAGE>

            (b) Cause. "Cause" means any of the following: (i) the failure by
you to substantially perform your duties with the Company (other than due to
your incapacity as a result of physical or mental illness for a period not to
exceed 90 days); (ii) the engaging by you in conduct which is materially
injurious to the Company, its business or reputation, or which constitutes gross
misconduct; (iii) your material breach of the terms of this Agreement, the
Invention Agreement or any other agreements between you and the Company; (iv)
the material breach or taking of any action in material contravention of the
policies of the Company adopted by the Board of Directors or any committee
thereof, including, without limitation, the Company's Code of Ethics, Insider
Trading Compliance Program, Disclosure Process and Procedures or Corporate
Governance Guidelines; (v) your conviction for or admission or plea of no
contest with respect to a felony; or (vi) an act of fraud against the Company,
the misappropriation of material property belonging to the Company, or an act of
violence against an officer, director, employee or consultant of the Company;
provided, however, that in the event that any of the foregoing events in (i),
(iii) or (iv) is capable of being cured, the Company shall provide written
notice to you describing the nature of such event, and you shall thereafter have
thirty (30) business days to cure such event.

            (c) Change of Control. "Change of Control" means the occurrence of
any of the following:

                  (i) Any "person" (as such term is used in Sections 13(d) and
14(d) of the Securities Exchange Act of 1934, as amended) becomes the
"beneficial owner" (as defined in Rule 13d-3 under said Act), directly or
indirectly, of securities of the Company representing fifty percent (50%) or
more of the total voting power represented by the Company's then outstanding
voting securities; or

                  (ii) Any action or event occurring within a two-year period,
as a result of which fewer than a majority of the directors are Incumbent
Directors. "Incumbent Directors" shall mean directors who either (A) are
directors of the Company as of the date hereof, or (B) are elected, or nominated
for election, to the Board with the affirmative votes of at least a majority of
the Incumbent Directors at the time of such election or nomination (but shall
not include an individual whose election or nomination is in connection with an
actual or threatened proxy contest relating to the election of directors to the
Company); or

                  (iii) The consummation of a merger or consolidation of the
Company with any other corporation, other than a merger or consolidation which
would result in the voting securities of the Company outstanding immediately
prior thereto continuing to represent (either by remaining outstanding or by
being converted into voting securities of the surviving entity) at least fifty
percent (50%) of the total voting power represented by the voting securities of
the Company or such surviving entity outstanding immediately after such merger
or consolidation; or

                  (iv) The consummation of the sale, lease or other disposition
by the Company of all or substantially all the Company's assets.

            (d) Disability. "Disability" shall mean that Executive has been
unable to perform his Company duties as the result of his incapacity due to
physical or mental illness, and such inability, at least twenty-six (26) weeks
after its commencement, is determined to be total and permanent by a physician
selected by the Company or its insurers and reasonably acceptable to Executive
or

                                                                             -6-
<PAGE>

Executive's legal representative. Termination resulting from Disability may only
be effected after at least thirty (30) days' written notice by the Company of
its intention to terminate Executive's employment. In the event that Executive
resumes the performance of substantially all of his or her duties hereunder
before the termination of his or her employment becomes effective, the notice of
intent to terminate shall automatically be deemed to have been revoked.

            (e) Good Reason. "Good Reason" means any of the following unless
such event is agreed to, in writing or as set forth below, by you: (i) a
material reduction in your salary or benefits (excluding the substitution of
substantially equivalent compensation and benefits), other than as a result of a
reduction in compensation affecting employees of the Company, or its successor
entity, generally; (ii) a material diminution of your duties or responsibilities
relative to your duties and responsibilities in effect immediately prior to the
Change of Control, provided however, that, in the case of the Company being
acquired and made part of a larger organization, a change in your title or
reporting requirements where your duties, responsibilities and authority after
the Change of Control are functionally similar to your duties, responsibilities
and authority prior to the Change of Control (as, for example, when the
Vice-President, Sales of the Company remains responsible for sales of the
Company's products following a Change of Control but is not made the Vice
President, Sales of the acquiring corporation) shall not constitute "Good
Reason;" (iii) relocation of your place of employment to a location more than 50
miles from the Company's office location at the time of the Change of Control;
and (iv) failure of a successor entity in any Change of Control to assume and
perform under this Agreement. If any of the events set forth above shall occur,
you shall give prompt written notice of such event to the Company, or its
successor entity, and if such event is not cured within thirty (30) days from
such notice you may exercise your rights to resign for Good Reason, provided
that if you have not exercised such right within 45 days of the date of such
notice you shall be deemed to have agreed to the occurrence of such event.

      12. Arbitration.

            (a) General. In consideration of Executive's service to the Company,
its promise to arbitrate all employment related disputes and Executive's receipt
of the compensation, pay raises and other benefits paid to Executive by the
Company, at present and in the future, Executive agrees that any and all
controversies, claims, or disputes with anyone (including the Company and any
employee, officer, director, shareholder or benefit plan of the Company in their
capacity as such or otherwise) arising out of, relating to, or resulting from
Executive's service to the Company under this Agreement or otherwise or the
termination of Executive's service with the Company, including any breach of
this Agreement, will be subject to binding arbitration under the Arbitration
Rules set forth in California Code of Civil Procedure Section 1280 through
1294.2, including Section 1283.05 (the "RULES") and pursuant to California law.
Disputes which Executive agrees to arbitrate, and thereby agrees to waive any
right to a trial by jury, include any statutory claims under state or federal
law, including, but not limited to, claims under Title VII of the Civil Rights
Act of 1964, the Americans with Disabilities Act of 1990, the Age Discrimination
in Employment Act of 1967, the Older Workers Benefit Protection Act, the
California Fair Employment and Housing Act, the California Labor Code, claims of
harassment, discrimination or wrongful termination and any statutory claims.
Executive further understands that this Agreement to arbitrate also applies to
any disputes that the Company may have with Executive.

                                                                             -7-
<PAGE>

            (b) Procedure. Executive agrees that any arbitration will be
administered by the American Arbitration Association ("AAA") and that a neutral
arbitrator will be selected in a manner consistent with its National Rules for
the Resolution of Employment Disputes. The arbitration proceedings will allow
for discovery according to the rules set forth in the National Rules for the
Resolution of Employment Disputes or California Code of Civil Procedure.
Executive agrees that the arbitrator will have the power to decide any motions
brought by any party to the arbitration, including motions for summary judgment
and/or adjudication and motions to dismiss and demurrers, prior to any
arbitration hearing. Executive agrees that the arbitrator will issue a written
decision on the merits. Executive also agrees that the arbitrator will have the
power to award any remedies, including attorneys' fees and costs, available
under applicable law. Executive understands the Company will pay for any
administrative or hearing fees charged by the arbitrator or AAA except that
Executive will pay the first $125.00 of any filing fees associated with any
arbitration Executive initiates. Executive agrees that the arbitrator will
administer and conduct any arbitration in a manner consistent with the Rules and
that to the extent that the AAA's National Rules for the Resolution of
Employment Disputes conflict with the Rules, the Rules will take precedence.

            (c) Remedy. Except as provided by the Rules, arbitration will be the
sole, exclusive and final remedy for any dispute between Executive and the
Company. Accordingly, except as provided for by the Rules, neither Executive nor
the Company will be permitted to pursue court action regarding claims that are
subject to arbitration. Notwithstanding, the arbitrator will not have the
authority to disregard or refuse to enforce any lawful Company policy, and the
arbitrator will not order or require the Company to adopt a policy not otherwise
required by law which the Company has not adopted.

            (d) Availability of Injunctive Relief. In addition to the right
under the Rules to petition the court for provisional relief, Executive agrees
that any party may also petition the court for injunctive relief where either
party alleges or claims a violation of this Agreement or the Confidentiality
Agreement or any other agreement regarding trade secrets, confidential
information, nonsolicitation or Labor Code Section 2870. In the event either
party seeks injunctive relief, the prevailing party will be entitled to recover
reasonable costs and attorneys fees.

            (e) Administrative Relief. Executive understands that this Agreement
does not prohibit Executive from pursuing an administrative claim with a local,
state or federal administrative body such as the Department of Fair Employment
and Housing, the Equal Employment Opportunity Commission or the workers'
compensation board. This Agreement does, however, preclude Executive from
pursuing court action regarding any such claim.

            (f) Voluntary Nature of Agreement. Executive acknowledges and agrees
that Executive is executing this Agreement voluntarily and without any duress or
undue influence by the Company or anyone else. Executive further acknowledges
and agrees that Executive has carefully read this Agreement and that Executive
has asked any questions needed for Executive to understand the terms,
consequences and binding effect of this Agreement and fully understand it,
including that Executive is waiving Executive's right to a jury trial. Finally,
Executive agrees that Executive has been provided an opportunity to seek the
advice of an attorney of Executive's choice before signing this Agreement.

                                                                             -8-
<PAGE>

      13. Successors.

            (a) The Company's Successors. Any successor to the Company (whether
direct or indirect and whether by purchase, merger, consolidation, liquidation
or otherwise) to all or substantially all of the Company's business and/or
assets shall assume the obligations under this Agreement and agree expressly to
perform the obligations under this Agreement in the same manner and to the same
extent as the Company would be required to perform such obligations in the
absence of a succession. For all purposes under this Agreement, the term
"Company" shall include any successor to the Company's business and/or assets
which executes and delivers the assumption agreement described in this Section
13(a) or which becomes bound by the terms of this Agreement by operation of law.

            (b) The Executive's Successors. The terms of this Agreement and all
rights of Executive hereunder shall inure to the benefit of, and be enforceable
by, Executive's personal or legal representatives, executors, administrators,
successors, heirs, distributees, devisees and legatees.

      14. Notice.

            (a) General. Notices and all other communications contemplated by
this Agreement shall be in writing and shall be deemed to have been duly given
when personally delivered or when mailed by U.S. registered or certified mail,
return receipt requested and postage prepaid. In the case of Executive, mailed
notices shall be addressed to him or her at the home address which he or she
most recently communicated to the Company in writing. In the case of the
Company, mailed notices shall be addressed to its corporate headquarters, and
all notices shall be directed to the attention of its Chief Financial Officer.

            (b) Notice of Termination. Any termination by the Company for Cause
or by Executive for Good Reason or as a result of a voluntary resignation shall
be communicated by a notice of termination to the other party hereto given in
accordance with Section 14(a) of this Agreement. Such notice shall indicate the
specific termination provision in this Agreement relied upon, shall set forth in
reasonable detail the facts and circumstances claimed to provide a basis for
termination under the provision so indicated, and shall specify the termination
date (which shall be not more than thirty (30) days after the giving of such
notice).

      15. Miscellaneous Provisions.

            (a) No Duty to Mitigate. Executive shall not be required to mitigate
the amount of any payment contemplated by this Agreement, nor, except as
otherwise contemplated in this Agreement, shall any such payment be reduced by
any earnings that Executive may receive from any other source.

            (b) Waiver. No provision of this Agreement shall be modified, waived
or discharged unless the modification, waiver or discharge is agreed to in
writing and signed by Executive and by an authorized officer of the Company
(other than Executive). No waiver by either party of any breach of, or of
compliance with, any condition or provision of this Agreement by the other party

                                                                             -9-
<PAGE>

shall be considered a waiver of any other condition or provision or of the same
condition or provision at another time.

            (c) Headings. All captions and section headings used in this
Agreement are for convenient reference only and do not form a part of this
Agreement.

            (d) Entire Agreement. This Agreement and the Invention Agreement
constitute the entire agreement of the parties hereto and supersedes in their
entirety all prior representations, understandings, undertakings or agreements
(whether oral or written and whether expressed or implied) of the parties with
respect to the subject matter hereof. No future agreements between the Company
and Executive may supersede this Agreement, unless they are in writing and
specifically mentioned this Agreement.

            (e) Choice of Law. The laws of the State of California (without
reference to its choice of laws provisions) shall govern the validity,
interpretation, construction and performance of this Agreement.

            (f) Severability. The invalidity or unenforceability of any
provision or provisions of this Agreement shall not affect the validity or
enforceability of any other provision hereof, which shall remain in full force
and effect.

            (g) Withholding. All payments made pursuant to this Agreement will
be subject to withholding of applicable income and employment taxes.

            (h) Counterparts. This Agreement may be executed in counterparts,
each of which shall be deemed an original, but all of which together will
constitute one and the same instrument.

                  [Remainder of Page Intentionally Left Blank]

                                                                            -10-
<PAGE>

      IN WITNESS WHEREOF, each of the parties has executed this Agreement, in
the case of the Company by its duly authorized officer, as of the day and year
set forth below.

COMPANY                       CYTOKINETICS, INCORPORATED

                              By: /s/ James Sabry
                                  ------------------------------------
                              Title: President & CEO

EXECUTIVE                     By: /s/ Gail Sheridan
                                  ------------------------------------
                                  Gail Sheridan, Vice President, Human
                                  Resources

                                                                            -11-

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