<PAGE>   1
                                            ***Text Omitted and Filed Separately
                                                Confidential Treatment Requested
                                          Under 17 C.F.R. Sections 200.80(b)(4),
                                                            200.83 and 240.24b-2

                         LEASE AGREEMENT BY AND BETWEEN

                            HMS GATEWAY OFFICE L.P.,

                         A DELAWARE LIMITED PARTNERSHIP

                                AS LANDLORD, AND

                          COULTER PHARMACEUTICAL, INC.,

                             A DELAWARE CORPORATION

                                    AS TENANT

                             DATED NOVEMBER 7, 1997


<PAGE>   2
                                TABLE OF CONTENTS


<TABLE>
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BASIC LEASE INFORMATION ....................................................       IV

1.    DEMISE ...............................................................        1

2.    PREMISES .............................................................        1

3.    TERM .................................................................        2

4.    RENT .................................................................        2

            (A)   Base Rent and Letter of Credit ...........................        2

                        (1)   Base Rent ....................................        2

                        (2)   Letter of Credit .............................        3

            (B)   Additional Rent ..........................................        5

            (C)   Payment of Additional Rent ...............................        9

            (D)   General Payment Terms ....................................       10

            (E)   Audit ....................................................       10

5.    UTILITY EXPENSES .....................................................       11

6.    LATE CHARGE ..........................................................       11

7.    SECURITY DEPOSIT .....................................................       12

8.    POSSESSION ...........................................................       12

            (A)   Tenant's Right of Possession .............................       12

            (B)   Delay in Delivering Possession ...........................       12

            (C)   Time for Performance .....................................       13

            (D)   Outside Completion Date ..................................       13

9.    USE OF PREMISES ......................................................       13

            (A)   Permitted Use ............................................       13

            (B)   Compliance with Governmental Regulations and Private
                  Restrictions..............................................       14

            (C)   Compliance with Americans with Disabilities Act ..........       14

10.   ACCEPTANCE OF PREMISES ...............................................       15

11.   SURRENDER ............................................................       15

12.   ALTERATIONS AND ADDITIONS ............................................       17

13.   MAINTENANCE AND REPAIRS OF PREMISES ..................................       19

            (A)   Maintenance by Tenant ....................................       19

            (B)   Maintenance by Landlord ..................................       20
</TABLE>


                                        i.


<PAGE>   3
                                TABLE OF CONTENTS
                                   (CONTINUED)


<TABLE>
<CAPTION>
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<S>                                                                               <C>
            (C)   Tenant's Waiver of Rights ................................       20

14.   LANDLORD'S INSURANCE .................................................       21


15.   TENANT'S INSURANCE ...................................................       21

            (A)   Commercial General Liability Insurance ...................       21

            (B)   Personal Property Insurance ..............................       21

            (C)   Worker's Compensation Insurance; Employer's Liability
                  Insurance                                                        22

            (D)   Evidence of Coverage .....................................       22

16.   INDEMNIFICATION ......................................................       22

            (A)   Of Landlord ..............................................       22

            (B)   Of Tenant ................................................       23

            (C)   No Impairment of Insurance ...............................       23

17.   SUBROGATION ..........................................................       23

18.   SIGNS ................................................................       23

19.   FREE FROM LIENS ......................................................       23

20.   ENTRY BY LANDLORD ....................................................       24

21.   DESTRUCTION AND DAMAGE ...............................................       24

22.   CONDEMNATION .........................................................       26

23.   ASSIGNMENT AND SUBLETTING ............................................       27

24.   TENANT'S DEFAULT .....................................................       30

25.   LANDLORD'S REMEDIES ..................................................       32

            (A)   Termination ..............................................       32

            (B)   Continuation of Lease ....................................       33

            (C)   Re-entry .................................................       33

            (D)   Reletting ................................................       34

            (E)   Termination ..............................................       34

            (F)   Cumulative Remedies ......................................       34

            (G)   No Surrender .............................................       34

26.   LANDLORD'S RIGHT TO PERFORM TENANT'S OBLIGATIONS .....................       35

27.   ATTORNEY'S FEES ......................................................       35

28.   TAXES ................................................................       36
</TABLE>


                                      ii.


<PAGE>   4
                                TABLE OF CONTENTS
                                   (CONTINUED)


<TABLE>
<CAPTION>
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                                                                                  ----
<S>                                                                               <C>
29.   EFFECT OF CONVEYANCE .................................................       36

30.   TENANT'S ESTOPPEL CERTIFICATE ........................................       36

31.   SUBORDINATION ........................................................       37

32.   ENVIRONMENTAL COVENANTS ..............................................       37


33.   NOTICES ..............................................................       40

34.   WAIVER ...............................................................       40

35.   HOLDING OVER .........................................................       41

36.   SUCCESSORS AND ASSIGNS ...............................................       41

37.   TIME .................................................................       42

38.   BROKERS ..............................................................       42

39.   LIMITATION OF LIABILITY ..............................................       42

40.   FINANCIAL STATEMENTS .................................................       42

41.   RULES AND REGULATIONS ................................................       43

42.   MORTGAGEE PROTECTION .................................................       43

            (A)   Modifications for Lender .................................       43

            (B)   Rights to Cure ...........................................       43

43.   ENTIRE AGREEMENT .....................................................       43

44.   INTEREST .............................................................       44

45.   INTERPRETATION .......................................................       44

46.   REPRESENTATIONS AND WARRANTIES .......................................       44

            (A)   Of Tenant ................................................       44

            (B)   Of Landlord ..............................................       45

47.   SECURITY .............................................................       45

48.   JURY TRIAL WAIVER ....................................................       45

49.   OPTION TO RENEW ......................................................       46

50.   RIGHT OF FIRST NEGOTIATION ...........................................       47

51.   RIGHT OF FIRST OFFER .................................................       48

52.   RIGHT TO EXPAND ......................................................       49

53.   MEMORANDUM OF LEASE ..................................................       51
</TABLE>


                                      iii.


<PAGE>   5
                                 LEASE AGREEMENT

                             BASIC LEASE INFORMATION


Lease Date:                         November 7, 1997

Landlord:                           HMS Gateway Office, L.P.
                                    A Delaware Limited partnership

Landlord's Address:                 C/o Hines Interests Limited Partnership
                                    101 California Street, Suite 1000
                                    San Francisco, California 94111-5848
                                    Attn: Tom Kruggel            

                                    All notices sent to Landlord under this
                                    Lease shall be sent to the above address,
                                    with copies to:

                                    Hines Interests Limited Partnership
                                    101 California Street, Suite 1000
                                    San Francisco, California 94111-5848
                                    Attn: Paul Paradis Tenant:

Tenant:                             Coulter Pharmaceutical, Inc., 
                                    A Delaware corporation

Tenant's Contact Person:            William G. Harris

Tenant's Address and 
Telephone Number:                   550 California Avenue 
                                    Suite 200    
                                    Palo Alto, California 94306-1440
                                    (650) 842-7300


Premises Square Footage:            [...***...] square feet, subject to final
                                    determination by Landlord's Architect upon
                                    Commencement of the Term. Such measurement
                                    to be made in accordance with Landlord's
                                    Architect's standard measurement procedures
                                    or research and development space.

Premises Address:                   600 Gateway Boulevard
                                    South San Francisco, California

Project:                            Approximately 7.85 acres of land commonly
                                    known as Lot 2B of the Gateway Center and
                                    referred to as the Gateway Technology
                                    Center, together with the land and
                                    improvements on which the Project is
                                    situated and all Common Areas.

Building (if not the 
same as the Project):               600 Gateway Boulevard
                                    South San Francisco, California


                                      iv.


<PAGE>   6
Tenant's Proportionate 
Share of Project:                   [...***...] subject to adjustment in
                                    accordance with Paragraph 4(c)(3)

Tenant's Proportionate 
Share of Building:                  100%

Length of Term:                     [...***...]

Estimated Commencement Date:        August 15, 1998

Estimated Expiration Date:          [...***...]

Monthly Base Rent:                  The above Monthly Base Rent calculations are
                                    subject to change after final determination
                                    of the Premises Square Footage and any such
                                    adjustment shall be based on a Monthly Base
                                    Rent for the first Lease year of [...***...]
                                    per square foot multiplied by the Premises
                                    Square Footage, and each subsequent Lease
                                    Year being [...***...] of the preceding
                                    Lease Year's Monthly Base Rent.

Prepaid Rent:                       None

Prepaid Additional Rent:            None

Security Deposit:                   [...***...]

Permitted Use:                      General office and research and development
                                    activities associated with
                                    biotechnology/pharmaceutical services. All
                                    uses must be in accordance with zoning
                                    ordinances of the City of South San
                                    Francisco.

Unreserved Parking Spaces:          [...***...] non-exclusive and undesignated
                                    parking spaces.

Broker(s):                          CB Commercial Real Estate Group, Inc. CB
                                    Madison Advisory Group

Tenant's Allowance:                 [...***...]


                                       v.


<PAGE>   7
                                 LEASE AGREEMENT

        THIS LEASE AGREEMENT is made and entered into by and between Landlord
and Tenant on the Lease Date. The defined terms used in this Lease which are
defined in the Basic Lease Information attached to this Lease Agreement ("Basic
Lease Information") shall have the meaning and definition given them in the
Basic Lease Information. The Basic Lease Information, the exhibits, the addendum
or addenda described in the Basic Lease Information, and this Lease Agreement
are and shall be construed as a single instrument and are referred to herein as
the "Lease."

1.      DEMISE

        In consideration for the rents and all other charges and payments
payable by Tenant, and for the agreements, terms and conditions to be performed
by Tenant in this Lease, LANDLORD DOES HEREBY LEASE TO TENANT, AND TENANT DOES
HEREBY HIRE AND TAKE FROM LANDLORD, the Premises described below (the
"Premises"), upon the agreements, terms and conditions of this Lease for the
Term hereinafter stated.

2.      PREMISES

        The "Premises" demised by this Lease are to consist initially of that
certain building (the "Building") specified in the Basic Lease Information,
which Building is to be located in that certain real estate development (the
"Project") specified in the Basic Lease Information. If at any time during the
Term, Tenant is leasing, in accordance with the terms and conditions of this
Lease, less than all of the Building, the "Premises" shall be deemed to include
only that portion of the Building then leased by Tenant pursuant to this Lease.
Tenant shall have the non-exclusive right (in common with the other tenants,
Landlord and any other person granted use by Landlord) to use the Common Areas
(as hereinafter defined), except that, with respect to parking, Tenant shall
have only a license to use the number of non-exclusive and undesignated parking
spaces set forth in the Basic Lease Information in the Project's parking areas
(the "Parking Areas"); provided however, Landlord shall use commercially
reasonable efforts to enforce Tenant's right to use such parking spaces. No
easement for light or air is incorporated in the Premises. For purposes of this
Lease, the term "Common Areas" shall mean all areas and facilities outside the
Premises and within the exterior boundary line of the Project that are from time
to time provided and designated by Landlord for the non-exclusive use of
Landlord, Tenant and other tenants of the Project and their respective
employees, guests and invitees.

        Landlord shall cause the construction of the Base Building Improvements
in accordance with the terms and conditions of the Base Building Construction
Agreement attached hereto as Exhibit A. Additionally, Tenant shall cause the
construction of certain tenant improvements in the interior of the Premises in
accordance with the terms and conditions of the Premises Construction Agreement
attached hereto as Exhibit B.

        Except as otherwise provided in the last sentence of this Paragraph,
Landlord has the right, in its sole discretion, from time to time, to: (a) make
changes to the Common Areas, including, without limitation, changes in the
location, size, shape and number of driveways, entrances, parking spaces
(provided however, Landlord shall not have the right, except as 


                                       1.


<PAGE>   8
otherwise provided herein, to reduce the total number of parking spaces below
the number allocated to Tenant in the Basic Lease Information) parking areas,
ingress, egress, direction of driveways, entrances, corridors and walkways; (b)
close temporarily any of the Common Areas for maintenance or construction
purposes so long as reasonable access to the Premises remains available; (c) add
additional buildings and improvements to the Common Areas or remove existing
buildings or improvements therefrom; (d) use the Common Areas while engaged in
making additional improvements, repairs or alterations to the Project or any
portion thereof so long as reasonable access to the Premises remains available;
and (e) do and perform any other acts or make any other changes in, to or with
respect to the Common Areas and the Project as Landlord may, in its sole
discretion, deem to be appropriate. Notwithstanding (a), and (c) above, Landlord
shall make no material changes or add additional buildings or material
improvements to any portion of the Common Areas described on the Site Plan, as
defined in the Base Building Construction Agreement, without obtaining Tenant's
consent, which consent shall not be unreasonably withheld, conditioned or
delayed; provided however, such consent shall not be required if any change or
addition is required or requested by a governmental agency having jurisdiction
over the Project or as required by law.

3.      TERM

        The term of this Lease (the "Term") shall be for the period of months
specified in the Basic Lease Information, commencing on, subject to Paragraph D
of Exhibit B, the earliest to occur of the following dates (the "Commencement
Date"):

        (A) The date the Tenant Improvements are approved by the appropriate
governmental agency as being in accordance with its building code and the
building permit issued for such improvements, as evidenced by the issuance of a
final building inspection approval; or

        (B) The date Tenant's Architect and Tenant's Contractor have both
certified in writing to Tenant that the Tenant Improvements have been
substantially completed in accordance with the plans and specifications
therefor; or

        (C) The date Tenant commences occupancy of the Premises.

        In the event the actual Commencement Date, as determined pursuant to the
foregoing, is a date other than the Estimated Commencement Date, then Landlord
and Tenant shall promptly execute a Commencement and Expiration Date Memorandum
in the form attached hereto as Exhibit D, wherein, the parties shall specify the
Commencement Date, the date on which the Term expires (the "Expiration Date")
and the date on which Tenant is to commence paying Rent.

4.      RENT

        (A) BASE RENT AND LETTER OF CREDIT.

          (1) BASE RENT. Tenant shall pay to Landlord, in advance on the first
day of each month, without further notice or demand and without offset or
deduction, the monthly installments of rent specified in the Basic Lease
Information (the "Base Rent").


                                       2.


<PAGE>   9
          (2) LETTER OF CREDIT. Concurrently with execution hereof, Tenant shall
deliver to Landlord, at Tenant's sole cost and expense, the Letter of Credit
described below in the amount of [...***...] as security for the full and
faithful performance of Tenant's covenants and Obligations under this Lease.
Upon the earlier of Tenant's delivery to Landlord of a Guaranty by a Qualified
Corporate Partner or forty-five (45) days after the expiration of the Term or
earlier termination, the Letter of Credit shall be returned to Tenant, reduced
by any amounts that Landlord reasonably estimates to be required to remedy any
defaults on the part of Tenant hereunder. The portion of the Letter of Credit
not so estimated to be required shall be paid over to Tenant within two (2)
weeks after expiration of the Term. Landlord may (but shall not be required to)
draw upon the Letter of Credit and use the proceeds therefrom (the "Letter of
Credit Proceeds") or any portion thereof to cure any default under this Lease
and to compensate Landlord for any damage Landlord incurs as a result of such
default, it being understood that any use of the Letter of Credit Proceeds shall
not constitute a bar or defense to any of Landlord's remedies set forth in this
Lease. In such event and upon written notice from Landlord to Tenant specifying
the amount of the Letter of Credit Proceeds so utilized by Landlord, Tenant
shall immediately deliver to Landlord an amendment to the Letter of Credit or a
replacement Letter of Credit in an amount equal to [...***...] of the amount
specified below. Tenant's failure to deliver such replacement Letter of Credit
to Landlord within ten (10) days of Landlord's notice shall constitute a default
hereunder.

        As used herein, Letter of Credit shall mean an unconditional, stand-by
(hereinafter referred to as the "Letter of Credit") issued by a major national
bank mutually satisfactory to Landlord and Tenant (collectively, the "Bank"),
naming Landlord as beneficiary, in the amount of [...***...]. During the period
from the Commencement Date through the last day of the [...***...] Lease Year,
the amount of the Letter of Credit shall be reduced by [...***...] on the last
day of each such Lease Year. During the period from the [...***...] Lease
Year-through the Expiration Date, the amount of the Letter of Credit shall be
reduced by [...***...] on the last day of each such Lease Year. The Letter of
Credit shall be for a one-year term and in any event shall be maintained in
effect from the date hereof through the date that is forty-five (45) days after
expiration of the Term or earlier termination. The Letter of Credit shall
provide: (i) that Landlord may make partial and multiple draws thereunder, up to
the face amount thereof, (ii) that Landlord may draw upon the Letter of Credit
up to the full amount thereof, as determined by Landlord, and the Bank will pay
to Landlord the amount of such draw upon receipt by the Bank of a sight draft
signed by Landlord, accompanied by a written statement from Landlord that Tenant
is in default under the Lease, and (iii) that, in the event of Landlord's
assignment or other transfer of its interest in this Lease, the Letter of Credit
shall be freely transferable (with Tenant paying all costs and expenses charged
by the Bank in connection with any such transfer) Landlord, without recourse, to
the assignee or transferee of such interest and the Bank shall confirm the same
to Landlord and such assignee or transferee. In the event that the Bank shall
fail to notify Landlord at least forty-five (45) days prior to expiration of the
Letter of Credit that the Letter of Credit will be renewed for at least one (1)
year beyond the then applicable expiration date, and deliver to Landlord a
replacement Letter of Credit or a modification to the existing Letter of Credit
effectuating such renewal at least forty-five (45) days prior to expiration of
the Letter of Credit, and Tenant shall not have otherwise delivered to 


*CONFIDENTIAL TREATMENT REQUESTED


                                       3.


<PAGE>   10
Landlord, at least forty-five (45) days prior to the relevant annual expiration
date, a replacement Letter of Credit in the amount required hereunder and
otherwise meeting the requirements set forth above, then Landlord shall be
entitled to draw on the Letter of Credit as provided above, and shall hold the
proceeds of such draw as security for the full and faithful performance of
Tenant's obligations hereunder, until Tenant shall have provided a new Letter of
Credit, in which event Landlord shall promptly return the proceeds of such draw,
not otherwise used in accordance with the terms of the Lease, to Tenant.

        Notwithstanding the foregoing, at anytime after the commencement of the
Term, Landlord agrees to allow Tenant to replace the Letter of Credit as
required hereunder with an unconditional guaranty of Tenant's obligations under
this Lease in the form of Exhibit C (the "Guaranty"), from a Qualified Corporate
Partner. A Qualified Corporate Partner shall mean an Affiliate, as that term is
defined in Paragraph 23 below, that, at the time of executing the Guaranty, has:
[...***...]

        As used in the preceding paragraph, the following terms shall have the
meanings set forth below:

               "CASH AND CASH EQUIVALENTS" shall mean the aggregate amount of
        the following, to the extent owned by the Guarantor free and clear of
        all loans, repayment obligations, encumbrances and rights of others: (i)
        cash on hand; (ii) dollar demand deposits maintained in the United
        States with any commercial bank and dollar time deposits maintained in
        the United States with, or certificates of deposit having a maturity of
        one year or less issued by, any commercial bank or other financial
        institution acceptable to the Landlord; (iii) direct obligations of, or
        unconditionally guaranteed by, the United States and having a maturity
        of one year or less; and (iv) readily marketable commercial paper having
        a maturity of one year or less, issued by any corporation organized and
        existing under the laws of the United States or any state thereof or the
        District of Columbia and rated by Standard & Poor's or Moody's (or, if
        neither such organization shall rate such commercial paper at any time,
        rated by any nationally recognized rating organization in the United
        States) with the highest rating assigned by such organization.

               "REVENUES" shall mean increases in assets or decreases in
        liabilities from operation of Guarantor's business for the twelve (12)
        month period prior to the execution of the Guaranty, calculated in
        accordance with generally accepted accounting principles,
        consistently applied.

               "NET PROFITS" shall mean revenues, less the sum of expenses
        (including taxes, but excluding amortization and depreciation) and
        return of owners' equity, calculated in accordance with generally
        accepted accounting principles, consistently applied.


*CONFIDENTIAL TREATMENT REQUESTED


                                       4.


<PAGE>   11
        As used in this Lease, the term "LEASE YEAR" shall mean a period of
twelve (12) full calendar months commencing on the Commencement Date, and each
subsequent sequential twelve (12) full calendar month period thereafter.

     (B) ADDITIONAL RENT. This Lease is intended to be a triple-net Lease with
respect to Landlord; and subject to Paragraph 13(b) below, the Base Rent owing
hereunder is (1) to be paid by Tenant net of all costs and expenses relating to
Landlord's ownership and operation of the Project and the Building, and (2) not
to be reduced, offset or diminished, directly or indirectly, by any cost, charge
or expense payable hereunder by Tenant or by others in connection with the
Premises, the Building and/or the Project or any part thereof. The provisions of
this Paragraph 4(b) for the payment of Tenant's Proportionate Share(s) of
Expenses (as hereinafter defined) are intended to pass on to Tenant its share of
all such costs and expenses. In addition to the Base Rent, Tenant shall pay to
Landlord, in accordance with this Paragraph 4, Tenant's Proportionate Share(s)
of all costs and expenses paid or incurred in connection with the operation,
maintenance, management and repair of the Premises, the Building and/or the
Project or any part thereof (collectively, the "Expenses"), including, without
limitation, all the following items (Tenant's Proportionate Share(s) of the
Expenses is hereinafter referred to as "Additional Rent"):

          (1) All supplies, materials and rental equipment used in the operation
and maintenance of the Project.

          (2) Utilities, that are not separately metered to Tenant, including,
without limitation, water, power, gas, sewer, waste disposal, communication and
cable T.V. facilities, heating, cooling, lighting and ventilation of the
Project.

          (3) A management fee equal to [...***...] of the annual Base Rent
derived from the Building; and all wages, salaries and other compensation for
any employees who provide service to the Building and/or the Project; provided
such wages, salads and other compensation shall not exceed [...***...] in any
given year (the "Wage Ceiling) (such Wage Ceiling to increase each year by
[...***...] of the Wage Ceiling for the preceding year).

          (4) Legal and accounting services for the Project, including, but not
limited to, the costs of audits by certified public accountants of Basic
Operating Cost records; provided, however, that legal expense shall not include
the cost of (i) negotiating lease terms for prospective tenants, (ii)
negotiating termination or extension of leases with existing tenants, (iii)
proceedings against any other specific tenant relating to such tenant's breach
of its lease, including without limitation failure to pay rent or other sums due
to Landlord from such tenant, or (iv) legal costs incurred in connection with
development and/or construction of the Project.

          (5) All insurance premiums and costs, including but not limited to,
the premiums and costs of fire, casualty, liability, rental abatement and
earthquake insurance applicable to the Project and Landlord's personal property
used in connection therewith (and all mounts paid as a result of loss sustained
that would be covered by such policies but for "deductible" or self-insurance
provisions); provided, however, that Landlord may, but shall not be obligated
to, carry earthquake 


*CONFIDENTIAL TREATMENT REQUESTED


                                       5.


<PAGE>   12
insurance. Notwithstanding the foregoing, if Landlord elects to carry earthquake
insurance, Tenant shall only be obligated to pay the following amounts on
account of such earthquake insurance during any calendar year: (i) if the
premiums and costs associated with the earthquake insurance for the Building
carried by Landlord for any given year are equal to or less than the Break Point
defined below, Tenant shall pay [...***...] of such premiums and costs as
Additional Rent; or (ii) if the premiums and costs associated with the
earthquake insurance for the Building carried by Landlord for any given year
exceed the Break Point, Tenant shall only pay [...***...] of such premiums and
costs as-Additional Rent. For purposes of this provision, "Break Point") shall
equal [...***...] (such amount to increase each year by [...***...] of the Break
Point for the preceding year). By way of example, if the premium and costs for
earthquake insurance carried by Landlord in a calendar year are [...***...],
Tenant shall be responsible for payment [...***...] as Additional Rent; however,
if the premiums and costs for earthquake insurance carried by Landlord in a
calendar year are [...***...], Tenant shall be responsible for paying
[...***...] as Additional Rent. If for any reason the earthquake insurance
carried by Landlord is part of an umbrella or overall insurance policy covering
the Building, the Project and other buildings, the determination of premiums and
costs shall be based on the allocated portion of the premium and costs with
respect to the Building, as reasonably determined by Landlord.

          (6) Repairs, replacements and general maintenance (except for repairs
and replacements (i) paid for from the proceeds of insurance, (ii) paid for
directly by Tenant, other tenants or any third party, or (iii) for the benefit
solely of tenants of the Project other than Tenant to the extent that Tenant
could not obtain similar services from Landlord without an obligation to
reimburse Landlord for the entire cost thereof under the provisions of this
Lease).

          (7) All real estate or personal property taxes, possessory interest
taxes, business or license taxes or fees, service payments in lieu of such taxes
or fees, annual or periodic license or use fees ("Real Property Taxes"),
including, but not limited to, all of the following: (i) all real estate taxes
and assessments, and all other taxes relating to, or levied, assessed or imposed
on, the Project, or any portion thereof, or interest therein; (ii) all taxes,
assessments, charges, levies, fees, excises or penalties, general and special,
ordinary and extraordinary, unforeseen as well as foreseen, of any kind and
nature imposed, levied upon, measured by or attributable to Landlord's
equipment, furniture, fixtures and other property located in, or used in
connection with, the Project, or levied upon, measured by or reasonably
attributable to the cost or value of any of the foregoing; (iii) all other
taxes, assessments, charges, levies, fees, or penalties, general and special,
ordinary and extraordinary, unforeseen as well as foreseen, of any kind and
nature imposed, levied, assessed, charged or collected by any governmental
authority or other entity either directly or indirectly (A) for public
improvements, user, maintenance or development fees, transit, housing,
employment, police, fire, open space, streets, sidewalks, utilities, job
training, child care or other governmental services or benefits, (B) upon or
with respect to the development, possession, leasing, operation, management,
maintenance, alteration, repair, use or occupancy of, or business operations in,
the Project (c) upon, against or measured by the area of the Project. or uses
made thereof. or leases made to tenants thereof, or all or any part of the rents
collected or collectible from tenants thereof, and (D) for environmental matters
or as a result of the imposition of mitigation measures, including parking
taxes, employer parking 


*CONFIDENTIAL TREATMENT REQUESTED


                                       6.


<PAGE>   13
regulations, or fees, charges or assessments as a result of the treatment of the
Project, or any portion thereof or interest therein, as a source of pollution or
storm water runoff; (iv) any tax or excise, however described, imposed in
addition to, or in substitution partially or totally of, any or all of the
foregoing taxes, assessments, charges or fees; and (v) any and all costs,
expenses and attorneys' fees paid or incurred by Landlord in connection with any
proceeding or action to contest in whole or in part, formally or informally, the
imposition, collection or validity of any of the foregoing taxes, assessments,
charges or fees. If by law any Real Property Taxes may be paid in installments
at the option of the taxpayer, then Landlord shall include within Real Property
Taxes only those installments (including interest, if any) which would become
due by exercise of such option. Real estate taxes shall not include (i)
inheritance or estate taxes imposed upon or assessed against the Project, or any
part thereof or interest therein, or (ii) taxes computed upon the basis of the
net income derived from the Project by Landlord or the owner of any interest
therein.

          (8) Amortization (together with reasonable financing charges) of
capital improvements made to the Premises, the Building or the Project
subsequent to the Commencement Date that (i) are or will be required to comply
with applicable law, ordinance rule or regulation, enacted or enforced after the
Commencement Date, (ii) are replacements of items which Landlord is obligated to
maintain; or (iii) are designed to improve the operating efficiency of the
Project ("Limited Capital Improvements"); provided, however, that in the case of
Limited Capital Improvements made solely for efficiency purposes, the amount
chargeable as an Expense in any year shall not exceed Landlord's reasonable
determination of the efficiency achieved either in direct cost savings,
avoidance of cost increases anticipated to be realized during the Term, or a
combination of both. As used in this Paragraph 4(b)(8), "amortization" shall
mean allocation of the cost equally to each year of useful life of the items
being amortized or a shorter period equal to the number of years required to
recover the cost of said item of capital improvement out of the savings in
operating efficiency derived therefrom.

          (9) Capital improvements to the Premises, the Building or the Project
which do not constitute Limited Capital Improvements and which, in the
aggregate, do not exceed [...***...] for the year in question.

        Notwithstanding any other provision herein to the contrary, if the
Project is not fully occupied during any year of the Term, an adjustment shall
be made in computing Additional Rent for such year so that Additional Rent shall
be computed as though the Project had been fully occupied during such year;
provided, however, that in no event shall Landlord collect in total, from Tenant
and all other tenants of the Project, an amount greater than [...***...] of the
actual Expenses during any year of the Term.

        Notwithstanding anything to the contrary contained in this Lease, the
following shall not be treated as Expenses for purposes of this Paragraph 4(b):

               (i) Leasing commissions, attorneys' fees, costs, disbursements,
and other expenses incurred in connection with negotiations or disputes with
tenants (other than 


*CONFIDENTIAL TREATMENT REQUESTED


                                       7.


<PAGE>   14
Tenant), or in connection with leasing, renovating, or improving space for
tenants or other occupants or prospective tenants or other occupants of the
Building.

               (ii) 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 escalations
payable under the lease with that tenant.

               (iii) Any depreciation on the Building or Project.

               (iv) Expenses in connection with services or other benefits of a
type that are not provided to Tenant but which are provided another tenant or
occupant of the Building or Project.

               (v) Costs incurred due to Landlord's violation of any terms or
conditions of this Lease or any other lease relating to the Building or Project.

               (vi) Overhead profit increments paid to Landlord's subsidiaries
or affiliates for management or other services on or to the Building 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.

               (vii) 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
due under any ground or underlying lease, or any lease for any equipment
ordinarily considered to be of a capital nature (except janitorial equipment
which is not affixed to the Building.)

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

               (ix) Advertising and promotional expenditures.

               (x) Costs of repairs and other work occasioned by fire,
windstorm, or other casualty that are insured or required to be insured by
Landlord hereunder, excluding any deductible.

               (xi) Any costs, fines, or penalties incurred due to violations by
Landlord of any governmental rule or authority, this Lease or any other lease in
the Project, or due to Landlord's gross negligence or willful misconduct.

               (xii) Costs for sculpture, paintings, or other objects of art
(nor insurance thereon or extraordinary security in connection therewith).

               (xiii) Wages, salaries, or other compensation paid to any
executive employees above the grade of building manager; provided however,
Landlord may charge as an Expense wages, salaries and other compensation for any
employees who provide service to the Building and/or Project in reasonable
proportion to the time spent in providing such service to the Building and/or
Project.



                                       8.


<PAGE>   15
               (xiv) The cost of correcting any building code or other
violations which were violations prior to the Commencement Date.

               (xv) The cost of containing, removing, or otherwise remediating
any contamination of the Project (including the underlying land and ground
water) by any Hazardous Materials either (i) where such contamination existed
prior to the date of this Lease or (ii) where such costs, in any given calendar
year, exceed, in the aggregate, [...***...]. Nothing in this provision shall be
deemed to limit Tenant's liability with respect to Hazardous Materials as set
forth in this Lease, including without limitation, Paragraph 16 and Paragraph 32
below.

               (xvi) Any other expense, except as otherwise specifically
provided for in this Lease, that under generally accepted accounting principles
and practice consistently applied would not be considered a normal maintenance
or operating expense.

     (C) PAYMENT OF ADDITIONAL RENT.

          (1) Upon commencement of this Lease, Landlord shall submit to Tenant
an estimate of monthly Additional Kent for the period between the Commencement
Date and the following December 31 and Tenant shall pay such estimated
Additional Kent on a monthly basis, in advance, on the first day of each month.
Tenant shall continue to make said monthly payments until notified by Landlord
of a change therein. By April 1 of each calendar year, Landlord shall endeavor
to provide to Tenant a statement (the "Expense Statement") showing the actual
Additional Rent due to Landlord for the prior calendar year, to be prorated
during the first year from the Commencement Date. If the total of the monthly
payments of Additional Rent that Tenant has made for the prior calendar year is
less than the actual Additional Rent chargeable to Tenant for such prior
calendar year, then Tenant shall pay the difference in a lump sum within ten
(10) days after receipt of such statement from Landlord. Any overpayment by
Tenant of Additional Rent for the prior calendar year shall be credited towards
the Additional Rent next due, or returned to Tenant in cash if no subsequent
Additional Rent will be payable.

          (2) Landlord's then-current annual operating and capital budgets for
the Building and the Project or the pertinent part thereof shall be used for
purposes of calculating Tenant's monthly payment of estimated Additional Rent
for the current year, subject to adjustment as provided above. Landlord shall
make the final determination of Additional Rent for the year in which this Lease
terminates as soon as possible after termination of such year. Even though the
Term has expired and Tenant has vacated the Premises, Tenant shall remain liable
for payment of any amount due to Landlord in excess of the estimated Additional
Rent previously paid by Tenant, and, conversely, Landlord shall promptly return
to Tenant any overpayment. Failure of Landlord to submit statements as called
for herein shall not be deemed a waiver of Tenant's obligation to pay Additional
Rent as herein provided.

          (3) With respect to Expenses which Landlord allocates to the Building,
Tenant's "Proportionate Share of the Building" shall be the percentage set forth
in the Basic Lease Information as Tenant's Proportionate Share of the Building,
as adjusted by Landlord from time to time as a result of changes in the square
footage leased by Tenant hereunder. With respect to 


*CONFIDENTIAL TREATMENT REQUESTED


                                       9.


<PAGE>   16
Expenses which Landlord allocates to the Project as a whole or to only a portion
of the Project, Tenant's "Proportionate Share of the Project" shall be, with
respect to Expenses which Landlord allocates to the Project as a whole, the
percentage set forth in the Basic Lease Information as Tenant's Proportionate
Share of the Project and, with respect to Expenses which Landlord allocates to
only a portion of the Project, a percentage calculated by Landlord from time to
time in its reasonable discretion and furnished to Tenant in writing (for
example, if the Building constitutes the only occupied premises of the Project,
Landlord may allocate [...***...] of such Expenses as lighting, landscaping and
Common Area maintenance to Tenant), in either case as adjusted by Landlord from
time to time for changes in the square footage leased by Tenant, addition of
improvements to the Project or changes in the physical size of the Project,
whether such changes in size are due to an addition to or a sale or conveyance
of a portion of the Project or otherwise. Notwithstanding the foregoing,
Landlord may equitably adjust Tenant's Proportionate Share of the Building or of
the Project, as applicable, for all or part of any item of expense or cost
reimbursable by Tenant that relates to a repair, replacement, or service that
benefits only the Premises.

     (D) GENERAL PAYMENT TERMS. The Base Rent, Additional Rent and all other
sums payable by Tenant to Landlord hereunder, including, without limitation, any
Late Charges, as defined below, assessed pursuant to Paragraph 6 below and any
interest assessed pursuant to Paragraph 44 below, are referred to as the "Rent".
All Rent shall be paid without deduction, offset or abatement in lawful money of
the United States of America. Checks are to be made payable to HMS Gateway
Office, L.P. and shall be mailed: c/o Hines Interests Limited Partnership, 101
California Street, Suite 1000, San Francisco, California 94111-5848, Attn: Tom
Kruggel or to such other person or place as Landlord may, from time to time,
designate to Tenant in writing. The Rent for any fractional part of a calendar
month at the commencement or termination of the Lease term shall [se a prorated
amount of the Rent for a full calendar month based upon the number of days in
the month of the commencement or termination of the Lease term, as applicable.

     (E) AUDIT. Provided Tenant is not in Default under the terms of this Lease,
Tenant, at its sole cost and expense, shall have the right within ninety (90)
days after the delivery of each Expense Statement to review and audit Landlord's
books and records regarding such Expense Statement for the sole purpose of
determining the accuracy of such Expense Statement. Such review or audit shall
be performed by a nationally recognized accounting firm that calculates its fees
with respect to hours actually worked and that does not discount its time or
rate (as opposed to a calculation based upon percentage of recoveries or other
incentive arrangement), shall take place during normal business hours in the
office of Landlord or Landlord's property manager and shall be completed within
three (3) business days after the commencement thereof provided that Landlord or
Landlord's property manager has made the books and records regarding the Expense
Statement available for review. If Tenant does not so review or audit Landlord's
books and records, Landlord's Expense Statement shall be final and binding upon
Tenant. In the event that Tenant determines on the basis of its review of
Landlord's books and records that the amount of Expenses paid by Tenant pursuant
to this Paragraph 4 for the period covered by such Expense Statement is less
than or greater than the actual amount properly payable by Tenant under the


*CONFIDENTIAL TREATMENT REQUESTED


                                      10.


<PAGE>   17
terms of this Lease, Tenant shall promptly pay any deficiency to Landlord or
Landlord shall promptly refund any excess payment to Tenant and pay for any
reasonable audit expenses, if such excess payment exceeds the aggregate Expenses
in Landlord's Expense Statement by [...***...], as the case may be.

5.      UTILITY EXPENSES

     (A) Tenant shall pay the cost of all water, sewer use, sewer discharge
fees, gas, heat, electricity, refuse pick-up, janitorial service (including,
without limitation, exterior and interior window washing), telephone and all
materials and services or other utilities (collectively, "Utilities") billed or
metered separately to the Premises and/or Tenant, together with all taxes,
assessments, charges and penalties added to or included within such cost. Tenant
acknowledges that the Premises. The Building and/or the Project may become
subject to the rationing of Utility services or restrictions on Utility use as
required by a public utility company, governmental agency or other similar
entity having jurisdiction thereof. Tenant acknowledges and agrees that its
tenancy and occupancy hereunder shall be subject to such rationing or
restrictions as may be imposed upon Landlord, Tenant, the Premises, the Building
and/or the Project, and Tenant shall in no event be excused or relieved from any
covenant or obligation to be kept or performed by Tenant by reason of any such
rationing or restrictions. Tenant agrees to comply with energy conservation
programs implemented by Landlord by reason of rationing, restrictions or Laws.

     (B) Landlord shall not be liable for any loss, injury or damage to property
caused by or resulting from any variation, interruption, or failure of Utilities
due to any cause whatsoever, or from failure to make any repairs or perform any
maintenance. No temporary interruption or failure of such services incident to
the making of repairs, alterations, improvements, or due to accident, strike, or
conditions or other events shall be deemed an eviction of Tenant or relieve
Tenant from any of its obligations hereunder. In no event shall Landlord be
liable to Tenant for any damage to the Premises or for any loss, damage or
injury to any property therein or thereon occasioned by bursting, rupture,
leakage or overflow of any plumbing or other pipes (including, without
limitation, water, steam, and/or refrigerant lines), sprinklers, tanks, drains,
drinking fountains or washstands, or other similar cause in, above, upon or
about the Premises, the Building, or the Project, unless caused by Landlord's
gross negligence or willful misconduct.

6.      LATE CHARGE

        Notwithstanding any other provision of this Lease, Tenant hereby
acknowledges that late payment to Landlord of Rent, or other amounts due
hereunder will cause Landlord to incur costs not contemplated by this Lease, the
exact amount of which will be extremely difficult to ascertain. If any Rent or
other sums due from Tenant are not received by Landlord or by Landlord's
designated agent when due, then Tenant shall pay to Landlord a late charge equal
to [...***...] of such overdue amount (the Late Charge"), plus any costs and
reasonable attorneys' fees incurred by Landlord by reason of Tenant's failure to
pay Rent and/or other charges when due hereunder; provided however, Landlord
hereby waives its right to collect the first two (2) Late Charges payable by
Tenant hereunder during the Term. Landlord and Tenant hereby agree 


*CONFIDENTIAL TREATMENT REQUESTED


                                      11.


<PAGE>   18
that such late charges represent a fair and reasonable estimate of the cost that
Landlord will incur by reason of Tenant's late payment and shall not be
construed as a penalty. Landlord's acceptance of such late charges shall not
constitute a waiver of Tenant's default with respect to such overdue amount or
estop Landlord from exercising any of the other rights and remedies granted
under this Lease.

                   Initials: Landlord ________ Tenant ________

7.      SECURITY DEPOSIT

        Concurrently with Tenant's execution of the Lease, Tenant shall deposit
with Landlord the Security Deposit specified in the Basic Lease Information as
security for the full and faithful performance of each and every term, covenant
and condition of this Lease. Landlord may use, apply or retain the whole or any
part of the Security Deposit as may be reasonably necessary (a) to remedy
Tenant's default in the payment of any Rent, (b) to repair damage to the
Premises caused by Tenant, (c) to clean the Premises upon termination of this
Lease, provided that Tenant has, in the reasonable judgment of Landlord, not
cleaned the Premises in accordance with Paragraph II, (d) to reimburse Landlord
for the payment of any amount which Landlord may reasonably spend or be required
to spend by reason of Tenant's default, or (e) to compensate Landlord for any
other loss or damage which Landlord may suffer by reason of Tenant's default.
Should Tenant faithfully and fully comply with all of the terms, covenants and
conditions of this Lease, within thirty (30) days following the expiration of
the Term, the Security Deposit or any balance thereof shall be returned to
Tenant or, at the option of Landlord, to the last assignee of Tenant's interest
in this Lease. Landlord shall keep the Security Deposit separate from its
general funds and shall deposit such in a financial institution selected by
Landlord and Tenant shall be entitled to any interest paid by such Bank on the
Security Deposit and such interest shall be paid on an annual basis to Tenant by
Landlord concurrently with the delivery of the Expense Statement or credited
against any amounts owed by Tenant to Landlord as shown on such Expense
Statement. If Landlord so uses or applies all or any portion of said deposit,
within five (5) days after written demand therefor Tenant shall deposit cash
with Landlord in an amount sufficient to restore the Security Deposit to the
full extent of the above amount, and Tenant's failure to do so shall be a
default under this Lease. In the event Landlord transfers its interest in this
Lease, Landlord shall transfer the then remaining amount of the Security Deposit
to Landlord's successor in interest, and thereafter Landlord shall have no
further liability to Tenant with respect to such Security Deposit.

8.      POSSESSION

     (A) TENANT'S RIGHT OF POSSESSION. Subject to Paragraph 8(b), Tenant shall
be entitled to possession of the Premises upon commencement of the Term.

     (B) DELAY IN DELIVERING POSSESSION. If for any reason whatsoever, Landlord
cannot deliver possession of the Premises to Tenant on or before the Estimated
Commencement Date, this Lease shall not be void or voidable (except as otherwise
expressly provided in Paragraph 8(c) and (d) below), nor shall Landlord, or
Landlord's agents, advisors, employees, partners, shareholders, directors,
invitees or independent contractors (collectively, "Landlord's Agents"), be
liable to Tenant for any loss or damage resulting therefrom. Subject to
Paragraph D of 




                                      12.


<PAGE>   19
Exhibit B, Tenant shall not be liable for Rent until Landlord delivers
possession of the Premises to Tenant. The Expiration Date shall be extended by
the same number of days that Tenant's possession of the Premises was delayed
beyond the Estimated Commencement Date.

     (C) TIME FOR PERFORMANCE. The parties have set forth on Exhibit H certain
events which must occur prior to or during the construction of the Base Building
Improvements (each a "Condition"), together with certain dates upon which each
condition must be satisfied ("Initial Window Date"); provided however, if
Landlord is delayed in satisfying any Condition due to Tenant Delays or Force
Majeure Events (as defined in Exhibit B), all of the Initial Window Dates set
forth on Exhibit H shall be extended for a period equal to the length of such
delay. If any condition is not satisfied on or before its Initial Window Date,
Tenant shall have the right to terminate this Lease by delivering written notice
to Landlord within five (5) business days after expiration of the applicable
Initial Window Date. If Tenant does not deliver written notice of termination to
Landlord within such five day period, Tenant shall have waived its right to
terminate as a result of Landlord's failure to satisfy the particular Condition
in question, all rights and obligations of Landlord and Tenant shall continue in
full force and effect, including satisfaction of the remaining Conditions. If
Tenant timely elects to terminate this Lease, the Lease shall terminate and
Landlord shall promptly refund to Tenant all sums paid to Landlord by Tenant,
including without limitation Carry Costs, if any.

     (D) OUTSIDE COMPLETION DATE. Notwithstanding anything in this Lease to the
contrary, if Landlord has not obtained a temporary certificate of occupancy
relating to the Base Building Improvements on or before [...***...], either
Tenant or Landlord shall have the right to terminate this Lease by delivering
written notice to the other on or before [...***...]; provided, however, if
Landlord is delayed in obtaining the temporary certificate of occupancy relating
to the Base Building Improvements as a result of Tenant Delays, such date shall
be extended for a period equal to the length of any such Tenant Delay. If
neither party delivers written notice of termination to the other within such
time period, each party shall have waived its right to terminate and all rights
and obligations of Landlord and Tenant shall continue in full force and effect,
including satisfaction of the remaining Conditions. If either Tenant or Landlord
timely elects to terminate this Lease, the Lease shall terminate and Landlord
shall promptly refund to Tenant all sums paid to Landlord by Tenant, including
without limitation Carry Costs, if any.

9.      USE OF PREMISES

     (A) PERMITTED USE.  The use of the Premises by Tenant and Tenant's agents,
advisors, employees, partners, shareholders, directors, invitees and independent
contractors (collectively, "Tenant's Agents") shall be solely for the Permitted
Use specified in the Basic Lease Information and for no other use. Tenant shall
not permit any objectionable or unpleasant odor, smoke, dust, gas, noise or
vibration to emanate from or near the Premises. The Premises shall not be used
to create any nuisance or trespass, for any illegal purpose, for any purpose not
permitted by Laws, for any purpose that would invalidate the insurance or
increase the premiums for insurance on the Premises, the Building or the Project
or for any purpose or in any manner that would interfere with other tenants' use
or occupancy of the Project. Tenant agrees to pay to 


*CONFIDENTIAL TREATMENT REQUESTED


                                      13.


<PAGE>   20
Landlord, as Additional Rent, any increases in premiums on policies resulting
from Tenant's Permitted Use or any other use or action by Tenant or Tenant's
Agents which increases Landlord's premiums or requires additional coverage by
Landlord to insure the Premises. Tenant agrees not to overload the floor(s) of
the Building.

     (B) COMPLIANCE WITH GOVERNMENTAL REGULATIONS AND PRIVATE RESTRICTIONS.
Tenant and Tenant's Agents shall, at Tenant's expense, faithfully observe and
comply with (1) all municipal, state and federal laws, statutes, codes, rules,
regulations, ordinances, requirements, and orders (collectively, "Laws"), except
such laws applicable to the construction of the Base Building Improvements now
in force or which may hereafter be in force pertaining to the Premises or
Tenant's use of the Premises, the Building or the Project, including without
limitation, any Laws requiring installation of fire sprinkler systems, seismic
reinforcement and related alterations, whether substantial in cost or otherwise,
provided, however, that except as provided in Paragraph 9(c) below, Tenant shall
not be required to make or, except as provided in Paragraph 4 above, pay for,
structural changes to the Premises or the Building not related to Tenant's
specific use of the Premises unless the requirement for such changes is imposed
as a result of any improvements or additions made or proposed to be made at
Tenant's request; (2) all recorded covenants, conditions and restrictions
affecting the Project ("Private Restrictions") now in force or which may
hereafter be in force; and (3) any and all rules and regulations set forth in
Exhibit E and any other rules and regulations now or hereafter promulgated by
Landlord related to parking or the operation of the Premises, the Building
and/or the Project (collectively, the "Rules and Regulations"). The judgment of
any court of competent jurisdiction, or the admission of Tenant in any action or
proceeding against Tenant, whether Landlord be a party thereto or not, that
Tenant has violated any such Laws or Private Restrictions, shall be conclusive
of that fact as between Landlord and Tenant.

     (C) COMPLIANCE WITH AMERICANS WITH DISABILITIES ACT. Landlord and Tenant
hereby agree and acknowledge that the Premises, the Building and/or the Project
may be subject to, among other Laws, the requirements of the Americans with
Disabilities Act, a federal law codified at 42 U.S.C. 12101 et seq., including,
but not limited to Title III thereof, and all regulations and guidelines related
thereto, together with any and all laws, rules, regulations, ordinances, codes
and statutes now or hereafter enacted by local or state agencies having
jurisdiction thereof, including all requirements of Title 24 of the State of
California, as the same may be in effect on the date of this Lease and may be
hereafter modified, amended or supplemented (collectively, the "ADA"). Landlord
shall cause the Base Building Improvements to be constructed in compliance with
the ADA. Any Tenant Improvements to be constructed hereunder shall be in
compliance with the requirements of the ADA, and all costs incurred for purposes
of compliance therewith shall be a part of and included in the costs of the
Tenant Improvements. Tenant shall be solely responsible for conducting its own
independent investigation of this matter and for ensuring that the design of all
Tenant Improvements strictly complies with all requirements of the ADA. Subject
to reimbursement pursuant to Paragraph 4 above, if any barrier removal work or
other work is required to the Building, the Common Areas or the Project under
the ADA, then such work shall be the responsibility of Landlord; provided, if
such work is required under the ADA as a result of Tenant's use of the Premises
or any work or Alteration (as hereinafter defined) made to the Premises by or on
behalf of Tenant, then such work shall be performed by Landlord at the sole cost
and expense of Tenant. Except as otherwise expressly provided in this provision,
Tenant shall be responsible at its sole cost and 



                                      14.


<PAGE>   21
expense for fully and faithfully complying with all applicable requirements of
the ADA, including without limitation, not discriminating against any disabled
persons in the operation of Tenant's business in or about the Premises, and
offering or otherwise providing auxiliary aids and services as, and when,
required by the ADA. Within ten (10) days after receipt, Tenant shall advise
Landlord in writing, and provide Landlord with copies of (as applicable), any
notices alleging violation of the ADA relating to any portion of the Premises,
the Building or the Project; any claims made or threatened orally or in writing
regarding noncompliance with the ADA and relating to any portion of the
Premises, the Building, or the Project; or any governmental or regulatory
actions or investigations instituted or threatened regarding noncompliance with
the ADA and relating to any portion of the Premises, the Building or the
Project. Tenant shall and hereby agrees to protect, defend (with counsel
acceptable to Landlord) and hold Landlord and Landlord's Agents harmless and
indemnify Landlord and Landlord's Agents from and against all liabilities,
damages, claims, losses, penalties, judgments, charges and expenses (including
attorneys' fees, costs of court and expenses necessary in the prosecution or
defense of any litigation including the enforcement of this provision) arising
from or in any way related to, directly or indirectly, Tenant's or Tenant's
Agents' violation or alleged violation of the ADA. Landlord shall and hereby
agrees to protect, defend (with counsel acceptable to Tenant) and hold Tenant
and Tenant's Agents harmless and indemnify Tenant and Tenant's Agents from and
against all liabilities, damages, claims, losses, penalties, judgments, charges
and expenses (including attorneys' fees, costs of court and expenses necessary
in the prosecution or defense of any litigation including the enforcement of
this provision) arising from or in any way related to, directly or indirectly,
Landlord's failure to have the Building Improvements constructed in compliance
with the ADA.

10.     ACCEPTANCE OF PREMISES

By taking possession of the Premises hereunder Tenant accepts the Premises as
suitable for Tenant's intended use and as being in good and sanitary operating
order, condition and repair, AS IS, and without representation or warranty by
Landlord as to the condition, use or occupancy which may be made thereof, except
for Landlord's express obligations described in Exhibit A. Any exceptions to the
foregoing must be by written agreement executed by Landlord and Tenant.

11.     SURRENDER

     (A) Tenant agrees that on the last day of the Term, or on the sooner
termination of this Lease, Tenant shall surrender the Premises to Landlord (i)
in good condition and repair (damage by acts of God, fire, and normal wear and
tear excepted), but with all interior walls painted or cleaned so they appear
painted and, where appropriate, patched, any carpets cleaned, all floors cleaned
and waxed, and all plumbing fixtures in good condition and working order and,
where appropriate, capped, and (ii) otherwise in accordance with Paragraph
32(h). Normal wear and tear shall not include any damage or deterioration that
would have been prevented by proper maintenance by Tenant, or Tenant otherwise
performing all of its obligations under this Lease. On or before the expiration
or sooner termination of this Lease, Tenant shall, in accordance with this
Paragraph 11, and at Tenant's sole cost and expense, remove, and repair any
damage caused by such removal, (A) all of Tenant's Property (as hereinafter
defined) and Tenant's signage from the Premises, the Building and the Project
and (B) all Tenant Improvements and all Alterations required to be removed
pursuant to Paragraph 12 and Exhibit A. Any of Tenant's Property not 



                                      15.


<PAGE>   22
so removed by Tenant as required herein shall be deemed abandoned and may be
stored, removed, and disposed of by Landlord at Tenant's expense, and Tenant
waives all claims against Landlord for any damages resulting from Landlord's
retention and disposition of such property; provided, however, that Tenant shall
remain liable to Landlord for all costs incurred in storing and disposing of
such abandoned property of Tenant. All Tenant Improvements and Alterations
except those which Tenant is required to remove pursuant to Paragraph 12 and
Exhibit A shall remain in the Premises as the property of Landlord. If the
Premises are not surrendered at the end of the Term or sooner termination of
this Lease, and in accordance with the provisions of this Paragraph 11 and
Paragraph 32(h) below, Tenant shall indemnify, defend and hold Landlord harmless
from and against any and all loss or liability resulting from delay by Tenant in
so surrendering the Premises including, without limitation, any loss or
liability resulting from any claim against Landlord made by any succeeding
tenant or prospective tenant founded on or resulting from such delay and losses
to Landlord due to lost opportunities to lease any portion of the Premises to
any such succeeding tenant or prospective tenant, together with, in each case,
actual attorneys' fees and costs.

     (B) Notwithstanding Paragraph 1l(a) above, with respect to all R&D Space,
as defined below, within the Premises, Tenant shall, on the last day of the Term
or on the sooner termination of this Lease, surrender such space to Landlord as
follows:

          (1) The Allowable R&D Space, as defined below, shall be surrendered to
Landlord in the condition specified in Paragraphs 11 (a)(i) and (ii), above,
except that Tenant shall not be required to paint or patch any interior walls
located within the Allowable R&D Space.

          (2) The Additional R&D Space, as defined below, shall be surrendered
to Landlord in the conditions specified in Paragraphs 11 (a)(i) and (ii), above.
In addition, Tenant shall pay to Landlord on or before the last day of the Term
or on the sooner termination of this Lease, the costs, as reasonably determined
by Landlord, necessary to remove all Tenant Improvements and Alterations
required to be removed under Paragraph 12 and Exhibit A, and otherwise to
surrender the Premises in a condition ready for Landlord to commence build-out
of such space for a succeeding tenant.

          (3) The Converted Office Space, as defined below, shall be surrendered
to Landlord in the condition required of Additional R&D Space, as provided in
Paragraph 11(b)2 above; provided however, Tenant shall also pay to Landlord on
or before the last day of the Term or on the sooner termination of this Lease,
the Conversion Allowance, as defined below.

     (C) For the purposes of this Paragraph 11, the following definitions shall
apply:

          (1) ALLOWABLE R&D SPACE shall mean (i) that portion of R&D Space
within the original Premises (specifically excluding the Expansion Space, as
defined below) (the "Original Premises") that, in the aggregate, does not exceed
[...***...] square feet and (ii) that portion of R&D Space within the Expansion
Space-that, in the aggregate, does not exceed [...***...] square feet, the
location of which shall be reasonably designated by Landlord in a notice to
Tenant 


*CONFIDENTIAL TREATMENT REQUESTED


                                      16.


<PAGE>   23
given not later than ninety (90) days prior to the Expiration Date (except in
the event of a termination of this Lease prior to the scheduled Expiration Date,
in which event, no advance notice shall be required).

          (2) ADDITIONAL R&D SPACE shall mean that portion of R&D Space within
the Original Premises in excess of the maximum Allowable R&D Space under
Paragraph 1l(c)(1) above; provided that the Additional R&D Space shall not
exceed an aggregate of [...***...] square feet. The location of the Additional
R&D Space shall be reasonably designated by Landlord in a notice to Tenant given
not later than ninety (90) days prior to the Expiration Date (except in the
event of a termination of this Lease prior to the scheduled Expiration Date, in
which event, no advance notice shall be required).

          (3) CONVERTED OFFICE SPACE shall mean (i) that portion of R&D Space
within the Original Premises in excess of the maximum Additional R&D Space for
the Original Premises and (ii) that portion of K&D Space within the Expansion
Space in excess of the maximum Allowable R&D Space for the Expansion Space.

          (4) R&D SPACE shall mean space that has been improved for research,
development, engineering, evaluation and testing activities and that, without
reconfiguration, cannot be used for standard office use, all as determined by
Landlord in its reasonable discretion based upon market conditions generally
existing at the time.

          (5) CONVERSION ALLOWANCE shall be an amount, calculated upon
termination of the Lease, equal to the greater of (i) [...***...] multiplied by
the total square feet of Converted Office Space or (ii) [...***...] multiplied
by the number of full Lease Years expired at the termination of the Lease,
multiplied by the total square feet of Converted Office Space. By way of
example, if the Lease is terminated in the [...***...] Lease Year and the
Converted Office Space is [...***...] square feet, then the Conversion Allowance
would be [...***...] whichever is greater than [...***...].

     (D) If at any time during the Term, the total square footage of the R&D
Space in (i) the Original Premises exceeds [...***...] square feet or (ii) the
Expansion Space exceeds [...***...] square feet (each excess amount being
referred to as the "Excess R&D Space Square Footage"), Tenant shall deposit with
Landlord, as security for Tenant's surrender obligations under this Paragraph
11, an amount equal to the sum of [...***...] multiplied by the Excess R&D Space
Square Footage. Such amount shall be held by Landlord in an interest bearing
account, with all interest earned thereon to be held by Landlord, and such
amount, including interest, shall be subsequently applied or disbursed in
accordance with Paragraph 7.

12.     ALTERATIONS AND ADDITIONS

     (A) Tenant shall not make, or permit to be made, any alteration, addition
or improvement (hereinafter referred to individually as an "Alteration" and
collectively as the "Alterations") to the Premises or any part thereof without
the prior written consent of Landlord, which consent shall not be unreasonably
withheld, conditioned or delayed; provided, however, that Landlord 


*CONFIDENTIAL TREATMENT REQUESTED


                                      17.


<PAGE>   24
shall have the right in its sole and absolute discretion to consent or to
withhold its consent to any Alteration which affects the structural portions of
the Premises, the Building or the Project or the mechanical, electrical or
life-safety systems serving the Premises, the Building and/or the Project or any
portion thereof (the "Systems"). Notwithstanding the foregoing, but subject to
the conditions set forth below, Tenant may, without Landlord's consent, make
Alterations within the Premises provided that such Alterations (i) do not affect
the structural portions of the Premises, the Building or the Project or the
Systems, and (ii) the cost, on an individual project basis, of any Alteration,
is less than [...***...] and, in the aggregate for the Term, does not exceed
[...***...].

     (B) Any Alteration to the Premises shall be at Tenant's sole cost and
expense, in compliance with all applicable Laws and all requirements requested
by Landlord, including, without limitation, the requirements of any insurer
providing coverage for the Premises or the Project or any part thereof, and in
accordance with plans and specifications approved in writing by Landlord, which
approval shall not be unreasonably withheld, conditioned or delayed.
Notwithstanding the foregoing, with respect to Alterations that may be made
without Landlord's prior consent as permitted above, Landlord agrees that Tenant
shall not be required to submit plans and specifications for prior approval of
the Landlord and that Landlord shall not require prior approval of the
installing contractor; provided, however, if Tenant does not obtain the prior
approval of plans and specifications for any Alteration, then subject to the
terms of this Paragraph 12(b), Landlord may, by notice to Tenant given not later
than ninety (90) days prior to the Expiration Date (except in the event of a
termination of this Lease prior to the scheduled Expiration Date, in which event
no advance notice shall be required), require Tenant, at Tenant's expense, to
remove, and repair any damage caused by removal of, any and all such
Alterations. If Tenant does not obtain Landlord's prior consent as to the
installing contractor, Tenant shall be responsible for maintaining harmonious
labor relations with all contractors and service providers servicing the
Premises, Building and/or Project. In addition, with respect to any Alterations
made without Landlord's prior consent as permitted above, Tenant agrees to meet
with Landlord, at Landlord's request, not more than once in every calendar year,
to discuss any such Alterations that have been made to the Premises. In such
meeting, Tenant shall provide Landlord with "as-built" plans and, if requested
by Tenant, Landlord shall within 30 days of such meeting, provide Tenant with a
list of those Alterations reviewed by Landlord that will be required to be
removed upon termination of the Lease. Any Alterations requiring the prior
consent of Landlord shall contain a request that Landlord specify in writing to
Tenant those Alterations that Tenant will be required to remove in accordance
with Paragraph 1 l(a) upon expiration or sooner termination of this Lease. Upon
receipt of such request, Landlord shall make such determination and respond to
Tenant within five (5) business days of such request. Before Alterations may
begin, valid building permits or other permits or licenses required must be
furnished to Landlord, and, once the Alterations begin, Tenant will diligently
and continuously pursue their completion. Landlord may monitor construction of
the Alterations and Tenant shall reimburse Landlord for its costs (including,
without limitation, the costs of any construction manager retained by Landlord)
in reviewing plans and documents and in monitoring construction. Tenant shall
maintain during the course of construction, at its sole cost and expense,
builders' risk insurance for the amount of the completed value of the
Alterations on an all-risk non-reporting form covering all improvements under
construction, including building materials, and other insurance in amounts and
against 


*CONFIDENTIAL TREATMENT REQUESTED


                                      18.


<PAGE>   25
such risks as Landlord shall reasonably require in connection with the
Alterations. In addition to and without limitation on the generality of the
foregoing, Tenant shall ensure that its contractor(s) procure and maintain in
full force and effect during the course of construction a "broad form"
commercial general liability and property damage policy of insurance naming
Landlord, Tenant and Landlord's lenders as additional insureds. The minimum
limit of coverage of the aforesaid policy shall be in the amount of not less
than [...***...] for injury or death of one person in any one accident or
occurrence and in the amount of not less than [...***...] for injury or death of
more than one person in any one accident or occurrence, and shall contain a
severability of interest clause or a cross liability endorsement. Such insurance
shall further insure Landlord and Tenant against liability for property damage
of at least [...***...].

     (C) Except as otherwise expressly stated herein or agreed to between the
parties, all Alterations, including, but not limited to, heating, lighting,
electrical, air conditioning, fixed partitioning, drapery, wall covering and
paneling, built-in cabinet work and carpeting installations made by Tenant,
together with all property that has become an integral part of the Premises or
the Building, shall at once be and become the property of Landlord, and shall
not be deemed trade fixtures or Tenant's Property.

     (D) No private telephone systems, utilities and/or other related computer,
utility or telecommunications equipment or lines may be installed without
Landlord's prior written consent, which consent shall not be unreasonably
withheld, conditioned or delayed. If Landlord gives such consent, all equipment
must be installed within the Premises and, unless Landlord, at the time of
installation, notified Tenant in writing that removal would not be required,
removed upon the expiration or sooner termination of this Lease and the Premises
restored to the same condition as before such installation.

     (E) Notwithstanding anything herein to the contrary, before installing any
equipment or lights which generate an undue amount of heat in the Premises, or
if Tenant plans to use any high-power usage equipment in the Premises, Tenant
shall obtain the written permission of Landlord which permission shall not be
unreasonably withheld, conditioned or delayed. Landlord may refuse to grant such
permission unless Tenant agrees to pay the costs to Landlord for installation of
supplementary air conditioning capacity or electrical systems necessitated by
such equipment.

     (F) Tenant agrees not to proceed to make any Alterations, notwithstanding
consent from Landlord to do so, until Tenant notifies Landlord in writing of the
date Tenant desires to commence construction or installation of such Alterations
and Landlord has approved such date in writing, in order that Landlord may post
appropriate notices to avoid any liability to contractors or material suppliers
for payment for Tenant's improvements. Tenant will at all times permit such
notices to be posted and to remain posted until the completion of work.

13.     MAINTENANCE AND REPAIRS OF PREMISES

     (A) MAINTENANCE BY TENANT. Throughout the Term, Tenant shall, at its sole
expense, (1) keep and maintain in good order and condition the Premises, and
repair and replace every part 


*CONFIDENTIAL TREATMENT REQUESTED


                                      19.


<PAGE>   26
thereof, including interior glass, windows, window frames and casements,
interior doors and door frames and door closers; interior lighting (including,
without limitation, light bulbs and ballasts), the plumbing and electrical
systems exclusively serving the Premises, all communications systems serving the
Premises, signage, interior demising walls and partitions, equipment, interior
painting and interior walls and floors, and the roll-up doors, ramps and dock
equipment, including, without limitation, dock bumpers, dock plates, dock seals,
dock levelers and dock lights located in or on the Premises (excepting only
those portions of the Building or the Project to be maintained by Landlord, as
provided in Paragraph 13Co) below), (2) furnish all expendables, including light
bulbs, paper goods and soaps, used in the Premises, and (3) keep and maintain in
good order and condition, repair and replace all of Tenant's security systems in
or about or serving the Premises. Tenant shall not do nor shall Tenant allow
Tenant's Agents to do anything to cause any damage, deterioration or
unsightliness to the Premises, the Building or the Project.

     (B) MAINTENANCE BY LANDLORD. Subject to the provisions of Paragraphs 13(a),
21 and 22, and further subject to Tenant's obligation under Paragraph 4 to
reimburse Landlord, in the form of Additional Rent, for Tenant's Proportionate
Share of the Project and the Building, as applicable, of the cost and expense of
the following items, Landlord agrees to repair and maintain the following items:
exterior glass, windows, window frames and casements, exterior doors and door
frames and door closers; the roof coverings (provided that Tenant installs no
additional air conditioning or other equipment on the roof that damages the roof
coverings, in which event Tenant shall pay all costs resulting from the presence
of such additional equipment); the Systems serving the Premises and the
Building, excluding the plumbing and electrical systems exclusively serving the
Premises; and the Parking Areas, pavement, landscaping, sprinkler systems,
sidewalks, driveways, curbs, and lighting systems in the Common Areas. Subject
to the provisions of Paragraphs 13(a), 21 and 22, Landlord, at its own cost and
expense, agrees to repair and maintain the following items: the structural
portions of the roof (specifically excluding the roof coverings), the
foundation, the footings, the floor slab, and the load bearing walls and
exterior walls of the Building (excluding any glass and any routine maintenance,
including, without limitation, any painting, sealing, patching and waterproofing
of such walls). Notwithstanding anything in this Paragraph 13 to the contrary,
Landlord shall have the right to either repair or to require Tenant to repair
any damage to any portion of the Premises, the Building and/or the Project
caused by or created due to any act, omission, negligence or willful misconduct
of Tenant or Tenant's Agents and to restore the Premises, the Building and/or
the Project, as applicable, to the condition existing prior to the occurrence of
such damage; provided, however, that in the event Landlord elects to perform
such repair and restoration work, Tenant shall reimburse Landlord upon demand
for all costs and expenses incurred by Landlord in connection therewith.
Landlord's obligation hereunder to repair and maintain is subject to the
condition precedent that Landlord shall have received written notice of the need
for such repairs and maintenance and a reasonable time to perform such repair
and maintenance. Tenant shall promptly report in writing to Landlord any
defective condition known to it which Landlord is required to repair, and
failure to so report such defects shall make Tenant responsible to Landlord for
any liability incurred by Landlord by reason of such condition.

     (C) TENANT'S WAIVER OF RIGHTS. Tenant hereby expressly waives all rights to
make repairs at the expense of Landlord or to terminate this Lease, as provided
for in California Civil 


                                      20.


<PAGE>   27
Code Sections 1941 and 1942, and 1932(1), respectively, and any similar or
successor statute or law in effect or any amendment thereof during the Term.

14.     LANDLORD'S INSURANCE

        Landlord shall purchase and keep in force "all risk" property insurance
covering the Building and the Project. Tenant shall, at its sole cost and
expense, comply with any and all reasonable requirements pertaining to the
Premises, the Building and the Project of any insurer necessary for the
maintenance of reasonable fire and commercial general liability insurance.
covering the Building and the Project. Landlord, at Tenant's cost, may maintain
"Loss of Rents" insurance, insuring that the Rent will be paid in a timely
manner to Landlord for a period of at least twelve (12) months if the Premises,
the Building or the Project or any portion thereof are destroyed or rendered
unusable or inaccessible by any cause insured against under this Lease.
Notwithstanding the foregoing, in the event Tenant provides satisfactory
evidence to Landlord that Tenant maintains insurance reasonably acceptable to
Landlord insuring that the Rent will be paid in a timely manner to Landlord for
a period of at least twelve (12) months if the Premise, the Building or the
Project or any portion thereof are destroyed or rendered unusable or
inaccessible by any cause insured against under this Lease, Landlord will not
charge Tenant for the cost of maintaining "Loss of Rents" insurance; provided
however, if for any reason Tenant fails to maintain such insurance, Tenant shall
be responsible for payment of the Rent that would have been paid to Landlord had
Tenant maintained insurance for such lost Rent.

15.     TENANT'S INSURANCE

     (A) COMMERCIAL GENERAL LIABILITY INSURANCE.  Tenant shall, at Tenant's 
expense, secure and keep in force a Commercial General Liability insurance
policy covering the Premises, insuring Tenant, and naming Landlord and its
lenders as additional insureds, against liability arising out of the ownership,
use, occupancy or maintenance of the Premises. The minimum limit of coverage of
such policy shall be in the amount of not less than [...***...] for each
occurrence combined single limited for bodily injury and property damage, shall
include an extended liability endorsement providing contractual liability
coverage (which shall include coverage for Tenant's indemnification obligations
in this Lease), and shall contain a severability of interest clause or a cross
liability endorsement. Landlord may from time to time require reasonable
increases in any such limits if Landlord believes that additional coverage is
necessary or desirable. The limit of any insurance shall not limit the liability
of Tenant hereunder. No policy maintained by Tenant under this Paragraph 15(a)
shall contain a deductible greater than [...***...]. No policy shall be
cancelable without thirty (30) days prior written notice to Landlord. Such
policies of insurance shall be issued as primary policies and not contributing
with or in excess of coverage that Landlord may carry, by an insurance company
authorized to do business in the State of California for the issuance of such
type of insurance coverage and rated A:XIII or better in Best's Key Rating
Guide.

     (B) PERSONAL PROPERTY INSURANCE. Tenant shall maintain in full force and
effect on all of its personal property, furniture, furnishings, trade or
business fixtures, equipment and such 


*CONFIDENTIAL TREATMENT REQUESTED


                                      21.


<PAGE>   28
other items listed on Exhibit I (collectively, "Tenant's Property") located on
the Premises, a policy or policies of fire and extended coverage insurance with
water damage and sprinkler leakage coverage to the extent greater than
[...***...]. During the term of this Lease the proceeds from any such policy or
policies of insurance shall be used for the repair or replacement of the
fixtures and equipment so insured. Landlord shall have no interest in the
insurance upon Tenant's equipment and fixtures and will sign all documents
reasonably necessary in connection with the settlement of any claim or loss by
Tenant. Landlord will not carry insurance on Tenant's possessions.

     (C) WORKER'S COMPENSATION INSURANCE; EMPLOYER'S LIABILITY INSURANCE. Tenant
shall, at Tenant's expense, maintain in full force and effect worker's
compensation insurance with not less than the minimum limits required by law,
and employer s liability insurance with a minimum limit of coverage of
[...***...].

     (D) EVIDENCE OF COVERAGE. Tenant shall deliver to Landlord certificates of
insurance and true and complete copies of any and all endorsements required
herein for all insurance required to be maintained by Tenant hereunder at the
time of execution of this Lease by Tenant. Tenant shall, at least thirty (30)
days prior to expiration of each policy, furnish Landlord with certificates of
renewal or "binders" thereof. Each certificate shall expressly provide that such
policies shall not be cancelable except after thirty (30) days prior written
notice to Landlord and the other parties named as additional insurers as
required in this Lease (except for cancellation for nonpayment of premium, in
which event cancellation shall not take effect until at least ten (10) clays
notice has been given to Landlord).

16.     INDEMNIFICATION

     (A) OF LANDLORD. Tenant shall indemnify and hold harmless Landlord and
Landlord's Agents against and from any and all claims, liabilities, judgments,
costs, demands, causes of action and expenses (including, without limitation,
reasonable attorneys' fees) arising from (1) the use of the Premises, the
Building or the Project by Tenant or Tenant's Agents, or from any activity done,
permitted or suffered by Tenant or Tenant's Agents in or about the Premises, the
Building or the Project, and (2) any act, neglect, fault, willful misconduct or
omission of Tenant or Tenant's Agents, or from any breach or default in the
terms of this Lease by Tenant or Tenant's Agents, and (3) any action or
proceeding brought on account of any matter in items (1) or (2). If any action
or proceeding is brought against Landlord by reason of any such claim, upon
notice from Landlord, Tenant shall defend the same at Tenant's expense by
counsel reasonably satisfactory to Landlord. As a material part of the
consideration to Landlord, Tenant hereby releases Landlord and Landlord's Agents
from responsibility for, waives its entire claim of recovery for and assumes all
risk of (i) damage to property or injury to persons in or about the Premises,
the Building or the Project from any cause whatsoever (except that which is
caused by the gross negligence or willful misconduct of Landlord or Landlord's
Agents or by the failure of Landlord to observe any of the terms and conditions
of this Lease, if such failure has persisted for an unreasonable period of time
after written notice of such failure), or (ii) loss resulting from 


*CONFIDENTIAL TREATMENT REQUESTED


                                      22.


<PAGE>   29
business interruption or loss of income at the Premises. The obligations of
Tenant under this Paragraph 16 shall survive any termination of this Lease.

     (B) OF TENANT. Landlord shall indemnify and hold harmless Tenant and
Tenant's Agents against and from any and all claims, liabilities, judgments,
costs, demands, causes of action and expenses (including, without limitation,
reasonable attorneys' fees) relating to the Project and arising from the gross
negligence or willful misconduct of Landlord or Landlord's Agents, and any
action or proceeding brought on account of such claims. If any action or
proceeding is brought against Tenant by reason of any such claim, upon notice
from Tenant, Landlord shall defend the same at Landlord's expense by counsel
reasonably satisfactory to Landlord. The obligations of Landlord under this
Paragraph 16 shall survive any termination of this Lease.

     (C) NO IMPAIRMENT OF INSURANCE. The foregoing indemnity shall not relieve
any insurance carrier of its obligations under any policies required to be
carried by either party pursuant to this Lease, to the extent that such policies
cover the peril or occurrence that results in the claim that is subject to the
foregoing indemnity.

17.     SUBROGATION

Landlord and Tenant hereby mutually waive any claim against the other and its
Agents for any loss or damage to any of their property located on or about the
Premises, the Building or the Project that is caused by or results from perils
covered by the property insurance required to be carried by the respective
parties in accordance with Paragraphs 14 and 15 of this Lease, whether or not
due to the negligence of the other party or its Agents. Because the foregoing
waivers will preclude the assignment of any claim by way of subrogation to an
insurance company or any other person, each party now agrees to immediately give
to its insurer written notice of the terms of these mutual waivers and shall
have their insurance policies endorsed to prevent the invalidation of the
insurance coverage because of these waivers. Nothing in this Paragraph 17 shall
relieve a party of liability to the other for failure to carry insurance
required by this Lease.

18.     SIGNS

        Landlord shall install, at Landlord's expense, building signage and
monument signage reflecting Tenant's occupancy of the Premises mutually
acceptable to Landlord and Tenant and complying with all applicable Laws or any
covenants, conditions or restrictions effecting the Project. Tenant shall not
place or permit to be placed in, upon, or about the Premises, the Building or
the Project any exterior, decorations, balloons, flags, pennants, banners,
advertisements or notices, or erect or install any signs, windows or door
lettering, placards, decorations, or advertising media of any type which can be
viewed from the exterior the Premises without obtaining Landlord's prior written
consent.

19.     FREE FROM LIENS

        Tenant shall keep the Premises, the Building and the Project free from
any liens arising out of any work performed, material furnished or obligations
incurred by or for Tenant in accordance with the provisions of this Paragraph
19. In the event that Tenant shall not, within ten (10) days following the
imposition of any such lien, cause the lien to be released of record by payment
or posting of a proper bond, Landlord shall have in addition to all other
remedies 


                                      23.


<PAGE>   30
provided herein and by law the right but not the obligation to cause same to be
released by such means as it shall deem proper, including payment of the claim
giving rise to such lien. All such sums paid by Landlord and all expenses
incurred by it in connection therewith (including, without limitation,
attorneys' fees) shall be payable to Landlord by Tenant upon demand. Landlord
shall have the right at all times to post and keep posted on the Premises any
notices permitted or required by law or that Landlord shall deem proper for the
protection of Landlord, the Premises, the Building and the Project, from
mechanics' and materialmen's liens. Tenant shall give to Landlord at least five
(5) business days' prior written notice of commencement of any repair or
construction on the Premises.

20.     ENTRY BY LANDLORD

        Tenant shall permit Landlord and Landlord's Agents to enter into and
upon the Premises at all reasonable times, upon reasonable notice (except in the
case of an emergency, for which no notice shall be required), and subject to
Tenant's reasonable security arrangements, for the purpose of inspecting the
same or showing the Premises to prospective purchasers, lenders or tenants or to
alter, improve, maintain and repair the Premises or the Building as required or
permitted of Landlord under the terms hereof, or for any other business purpose,
without any rebate of Rent and without any liability to Tenant for any loss of
occupation or quiet enjoyment of the Premises thereby occasioned (except for
actual damages resulting from the gross negligence or willful misconduct of
Landlord); and Tenant shall permit Landlord to post notices of
non-responsibility and ordinary "for sale" or "for lease" signs. No such entry
shall be construed to be a forcible or unlawful entry into, or a detainer of,
the Premises, or an eviction of Tenant from the Premises. Landlord may
temporarily close entrances, doors, corridors, elevators or other facilities
without liability to Tenant by reason of such closure in the case of an
emergency and when Landlord otherwise reasonably deems such closure necessary.

21.     DESTRUCTION AND DAMAGE

     (A) If the Premises are damaged by fire or other perils covered by extended
coverage insurance, Landlord shall, at Landlord's option:

          (1) In the event of total destruction (which shall mean destruction or
damage in excess of [...***...] of the full insurable value thereof) of the
Premises, elect either to commence promptly to repair and restore the Premises
and prosecute the same diligently to completion, in which event this Lease shall
remain in full force and effect; or not to repair or restore the Premises, in
which event this Lease shall terminate. Landlord shall give Tenant written
notice of its intention within sixty (60) days after the date (the "Casualty
Discovery Date") Landlord obtains actual knowledge of such destruction. If
Landlord elects not to restore the Premises, this Lease shall be deemed to have
terminated as of the date of such total destruction.

          (2) In the event of a partial destruction (which shall mean
destruction or damage to an extent not exceeding [...***...] of the full
insurable value thereof) of the Premises for which Landlord will receive
insurance proceeds sufficient to cover the cost to repair and restore such
partial destruction and, if the damage thereto is such that the Premises may be
substantially 


*CONFIDENTIAL TREATMENT REQUESTED


                                      24.


<PAGE>   31
repaired or restored to its condition existing immediately prior to such damage
or destruction within one hundred eighty (180) days from the Casualty Discovery
Date, Landlord shall commence and proceed diligently with the work of repair and
restoration, in which event the Lease shall continue in full force and effect.
If such repair and restoration requires longer than one hundred eighty (180)
days or if the insurance proceeds therefor (,plus any amounts Tenant may elect
or is obligated to contribute) are not sufficient to cover the cost of such
repair and restoration, Landlord may elect either to so repair and restore, in
which event the Lease shall continue in full force and effect, or not to repair
or restore, in which event the Lease shall terminate. In either case, Landlord
shall give written notice to Tenant of its intention within sixty (60) days
after the Casualty Discovery Date. If Landlord elects not to restore the
Premises, this Lease shall be deemed to have terminated as of the date of such
partial destruction.

     (B) If the Premises are damaged by any peril not covered by extended
coverage insurance, and the cost to repair such damage exceeds any amount Tenant
may agree to contribute, Landlord may elect either to commence promptly to
repair and restore the Premises and prosecute the same diligently to completion,
in which event this Lease shall remain in full force and effect; or not to
repair or restore the Premises, in which event this Lease shall terminate.
Landlord shall give Tenant written notice of its intention within sixty (60)
days after the Casualty Discovery Date. If Landlord elects not to restore the
Premises, this Lease shall be deemed to have terminated as of the date on which
Tenant surrenders possession of the Premises to Landlord, except that if the
damage to the Premises materially impairs Tenant's ability to continue its
business operations in the Premises, then this Lease shall be deemed to have
terminated as of the date such damage occurred.

     (C) Notwithstanding anything to the contrary in this Paragraph 21, Landlord
shall have the option to terminate this Lease, exercisable by notice to Tenant
within sixty (60) days after the Casualty Discovery Date, in each of the
following instances:

          (1) If more than [...***...] of the full insurable value of the
Building is damaged or destroyed, regardless of whether or not the Premises are
destroyed.

          (2) If the Building or the Project or any portion thereof is damaged
or destroyed and the repair and restoration of such damage requires longer than
one hundred eighty (180) days from the Casualty Discovery Date.

          (3) If the Building or the Project or any portion thereof is damaged
or destroyed and the insurance proceeds therefor are not sufficient to cover the
costs of repair and restoration.

          (4) If the Building or the Project or any portion thereof is damaged
or destroyed during the last twelve (12) months of the Term.

     (D) In the event of repair and restoration as herein provided, the monthly
installments of Base Rent shall be abated proportionately in the ratio which
Tenant's use of the Premises is impaired during the period of such repair or
restoration, but only to the extent of rental abatement insurance proceeds
received by Landlord, provided, however, that Tenant shall not be 


*CONFIDENTIAL TREATMENT REQUESTED


                                      25.


<PAGE>   32
entitled to such abatement to the extent that such damage or destruction was
caused by the acts or inaction of Tenant or Tenant's Agents. The number of
parking spaces allocated to Tenant hereunder shall be reduced on a proportionate
basis in the event any of the parking spaces in the Parking Areas are eliminated
as a result of such damage or destruction affecting such Parking Areas. Except
as expressly provided in the immediately preceding sentence with respect to
abatement of Base Rent, Tenant shall have no claim against Landlord for, and
hereby releases Landlord and Landlord's Agents from responsibility for and
waives its entire claim of recovery for any cost, loss or expense suffered or
incurred by Tenant as a result of any damage to or destruction of the Premises,
the Building or the Project or the repair or restoration thereof, including,
without limitation, any cost, loss or expense resulting from any loss of use of
the whole or any part of the Premises, the Building or the Project and/or any
inconvenience or annoyance occasioned by such damage, repair or restoration
unless caused by the gross negligence or willful misconduct of Landlord.

     (E) If Landlord is obligated to or elects to repair or restore as herein
provided, Landlord shall repair or restore only the initial Tenant Improvements
constructed in the Premises pursuant to the terms of this Lease, substantially
to their condition existing immediately prior to the occurrence of the damage or
destruction; and Tenant may, but shall not be obligated to, promptly repair and
restore, at Tenant's expense, Tenant's Alterations which were not constructed by
Landlord.

     (F) Tenant hereby waives the provisions of California Civil Code Section
1932(2) and Section 1933(4) which permit termination of a lease upon destruction
of the leased premises, and the provisions of any similar law now or hereinafter
in effect, and the provisions of this Paragraph 21 shall govern exclusively in
case of such destruction.

     (G) If Landlord elects to repair or restore the Premises in accordance with
the terms and conditions set forth in this Paragraph 21 but fails to
substantially complete such repair or restoration within two hundred and seventy
(270) days after the Casualty Discovery Date (the "Repair Period") and such
damage to the Premises materially and adversely affects Tenant in the conduct of
its business operations, Tenant shall have the right to terminate this Lease by
providing written notice to Landlord within five (5) business days after the end
of the Repair Period, in which event this Lease shall terminate as of the date
of such casualty.

22.     CONDEMNATION

If [...***...] or more of the Premises or the Building or the parking areas for
the Building as shown on the Site Plan is taken for any public or quasi-public
purpose by any lawful governmental power or authority, by exercise of the right
of appropriation, inverse condemnation, condemnation or eminent domain, or sold
to prevent such taking (each such event being referred to as a "Condemnation"),
Landlord may, at its option, terminate this Lease as of the date title vests in
the condemning party. If [...***...] or more of the Premises is taken and if the
Premises remaining after such Condemnation and any repairs by Landlord would
materially and adversely affect Tenant in the conduct of its business
operations, Tenant shall have the right 


*CONFIDENTIAL TREATMENT REQUESTED


                                      26.


<PAGE>   33
to terminate this Lease as of the date title vests in the condemning party. If
either party elects to terminate this Lease as provided herein, such election
shall be made by written notice to the other party given within thirty (30) days
after the nature and extent of such Condemnation have been finally determined.
If neither Landlord nor Tenant elects to terminate this Lease to the extent
permitted above, Landlord shall promptly proceed to restore the Premises, to the
extent of any Condemnation award received by Landlord, to substantially the same
condition as existed prior to such Condemnation, allowing for the reasonable
effects of such Condemnation, and a proportionate abatement shall be made to the
Base Rent corresponding to the time during which, and to the portion of the
floor area of the Premises (adjusted for any increase thereto resulting from any
reconstruction) of which, Tenant is deprived on account of such Condemnation and
restoration, as reasonably determined by Landlord. In addition, the number of
parking spaces allocated to Tenant hereunder shall be reduced on a proportionate
basis in the event any of the parking spaces in the Parking Areas are taken or
otherwise eliminated as a result of any Condemnation affecting such Parking
Areas. Except as expressly provided in the immediately preceding sentence with
respect to abatement of Base Rent, Tenant shall have no claim against Landlord
for, and hereby releases Landlord and Landlord's Agents from responsibility for
and waives its entire claim of recovery for any cost, loss or expense suffered
or incurred by Tenant as a result of any Condemnation or the repair or
restoration of the Premises, the Building or the Project or the parking areas
for the Building or the Project following such Condemnation, including, without
limitation, any cost, loss or expense resulting from any loss of use of the
whole or any part of the Premises, the Building, the Project or the parking
areas and/or any inconvenience or annoyance occasioned by such Condemnation,
repair or restoration. The provisions of California Code of Civil Procedure
Section 1265.130, which allows either party to petition the Superior Court to
terminate the Lease in the event of a partial taking of the Premises, the
Building or the Project or the parking areas for the Building or the Project,
and any other applicable law now or hereafter enacted, are hereby waived by
Tenant.

     (A) Landlord shall be entitled to any and all compensation, damages,
income, rent, awards, or any interest therein whatsoever which may be paid or
made in connection with any Condemnation, and Tenant shall have no claim against
Landlord for the value of any unexpired term of this Lease or otherwise;
provided, however, that Tenant shall be entitled to receive any award separately
allocated by the condemning authority to Tenant for Tenant's relocation expenses
or the value of Tenant's Property (specifically excluding fixtures, Alterations
and other components of the Premises which under this Lease or by law are or at
the expiration of the Term will become the property of Landlord), provided that
such award does not reduce any award otherwise allocable or payable to Landlord.

23.     ASSIGNMENT AND SUBLETTING

     (A) Except as specifically provided for in (b) below, Tenant shall not
voluntarily or by operation of law, (1) mortgage, pledge, hypothecate or
encumber this Lease or any interest herein, (2) assign or transfer this Lease or
any interest herein, sublease the Premises or any part thereof, or any right or
privilege appurtenant thereto, or allow any other person (the employees and
invitees of Tenant excepted) to occupy or use the Premises, or any portion
thereof, without first obtaining the written consent of Landlord, which consent
shall not be unreasonably withheld, conditioned or delayed provided that Tenant
is not then in Default under this Lease nor is any event then occurring which
with the giving of notice or the passage of time, or both, would 


                                      27.


<PAGE>   34
constitute a Default hereunder. When Tenant requests Landlord's consent to such
assignment or subletting, it shall notify Landlord in writing of the name and
address of the proposed assignee or subtenant and the nature and character of
the business of the proposed assignee or subtenant and shall provide current and
prior financial statements for the proposed assignee or subtenant prepared in
accordance with generally accepted accounting principles, consistently applied.
Tenant shall also provide Landlord with a copy of the proposed sublease or
assignment agreement, including all material terms and conditions thereof. In
the event Tenant wishes to assign or sublet the entire Premises for the
remainder of the Term (except in either event in connection with a Permitted
Transfer) Landlord shall have the option, to be exercised within thirty (30)
clays of receipt of the foregoing, to (1) terminate this Lease in its entirety,
(2) sublease or take an assignment, as the case may be, from Tenant of the
interest, in this Lease and/or the Premises that Tenant proposes to assign or
sublease, on the same terms and conditions as stated in the proposed sublet or
assignment agreement, (3) consent to the proposed assignment or sublease, or (4)
refuse its consent to the proposed assignment or sublease, providing that such
consent shall not be unreasonably withheld, conditioned or delayed so long as
Tenant is not then in Default under this Lease nor is any event then occurring
which with the giving of notice or the passage of time, or both, would
constitute a Default hereunder. In the event Landlord elects to terminate this
Lease or sublease or take an assignment from Tenant of the interest in the Lease
and/or the Premises that Tenant proposes to assign or sublease as provided in
the foregoing clauses (1) and (2), respectively, then Landlord shall have the
additional right to negotiate directly with Tenant's proposed assignee or
subtenant and to enter into a direct lease or occupancy agreement with such
party on such terms as shall be acceptable to Landlord in its sole and absolute
discretion, and Tenant hereby waives any claims against Landlord related
thereto, including, without limitation, any claims for any compensation or
profit related to such lease or occupancy agreement.

     (B) Without otherwise limiting the criteria upon which Landlord may
withhold its consent, Landlord shall be entitled to consider all reasonable
criteria including, but not limited to, the following: (1) whether or not the
proposed subtenant or assignee is engaged in a business which, and the use of
the Premises will be in an manner which, is in keeping with the then character
and nature of all other tenancies in the Project, (2) whether the use to be made
of the Premises by the proposed subtenant or assignee will conflict with any
so-called "exclusive" use then in favor of any other tenant of the Building or
the 'Project, and whether such use would be prohibited by any other portion of
this Lease, including, but not limited to, any rules and regulations then in
effect, or under applicable Laws, and whether such use imposes an unreasonable
load upon the Premises and the Building and Project services, (3) the business
reputation of the proposed individuals who will be managing and operating the
business operations of the assignee or subtenant, and the long-term financial
and; competitive business prospects of the proposed assignee or subtenant, and
(4) the creditworthiness and financial stability of the proposed assignee or
subtenant in light of the responsibilities involved. In any event, Landlord may
withhold its consent to any assignment or sublease, if the actual use proposed
to be conducted in the Premises or portion thereof conflicts with the provisions
of Paragraph 9(a) or (b) above or with any other lease which restricts the use
to which any space in the Building or the Project may be put. Notwithstanding
the foregoing, Tenant may, without Landlord's consent, but upon notice and
delivery of evidence documenting such assignment or subletting, assign or sublet
to an Affiliate (as defined below) of the original Tenant, provided that such
Affiliate has a net worth (calculated in accordance .with generally accepted
accounting 


                                      28.


<PAGE>   35
principles, consistently applied) equal to or greater than the net worth of the
original Tenant on the Commencement Date or the date of the proposed assignment
or subletting, whichever is higher (such assignment or subletting being referred
to as a "Permitted Transfer"). For purposes hereof, "Affiliate" shall mean any
person, firm or corporation (i) which shall be controlled by, under the control
of, or under common control with the original Tenant, (ii) which results from a
merger of, reorganization of, or consolidation with the original Tenant or (iii)
which acquires substantially all of the stock or assets of the original Tenant.
For purposes hereof, "control" shall mean the possession, direct or indirect, of
the power to direct or cause the direction of the management and policies of a
person, firm or corporation, whether through the ownership of voting securities,
by contract or otherwise.

     (C) If Landlord approves an assignment or subletting as herein provided,
Tenant shall pay to Landlord, as Additional Rent, all of the difference, if any,
between (1) the Base Rent plus Additional Rent allocable to that part of the
Premises affected by such assignment or sublease pursuant to the provisions of
this Lease, and (2) the rent and any additional rent payable by the assignee or
sublessee to Tenant, less actual leasing commissions, reasonable attorneys'
fees, tenant improvement costs and other reasonable out-of-pocket expenses, if
any, incurred by Tenant in connection with such assignment or sublease as
evidenced by written records reasonably satisfactory to Landlord. The assignment
or sublease agreement, as the case may be, after approval by Landlord, shall not
be amended without Landlord's prior written consent, which consent shall not be
unreasonably withheld, conditioned or delayed, and shall contain a provision
directing the assignee or subtenant to pay the rent and other sums due
thereunder directly to Landlord upon receiving written notice from Landlord that
Tenant is in default under this Lease with respect to the payment of Rent. In
the event that, notwithstanding the giving of such notice, Tenant collects any
rent or other sums from the assignee or subtenant, then Tenant shall hold such
sums in trust for the benefit of Landlord and shall immediately forward the same
to Landlord. Landlord's collection of such rent and other sums shall not
constitute an acceptance by Landlord of attornment by such assignee or
subtenant. A consent to one assignment, subletting, occupation or use shall not
be deemed to be a consent to any other or subsequent assignment, subletting,
occupation or use, and consent to any assignment or subletting shall in no way
relieve Tenant of any liability under this Lease. Any assignment or subletting
without Landlord's consent shall be void, and shall, at the option of Landlord,
constitute a Default under this Lease.

     (D) Notwithstanding any assignment or subletting, Tenant and any guarantor
or surety of Tenant's obligations under this Lease shall at all times remain
fully responsible and liable for the payment of the Rent and for compliance with
all of Tenant's other obligations under this Lease (regardless of whether
Landlord's approval has been obtained for any such assignment or subletting).

     (E) Tenant shall pay Landlord's reasonable fees (including, without
limitation, the fees of Landlord's counsel), incurred in connection with
Landlord's review and processing of 


                                      29.


<PAGE>   36
documents regarding any proposed assignment or sublease, which fees shall not
exceed [...***...].

     (F) Notwithstanding anything in this Lease to the contrary, in the event
Landlord consents to an assignment or subletting by Tenant in accordance with
the terms of this Paragraph 23, Tenant's assignee or subtenant shall have no
right to further assign this Lease or any interest therein or thereunder or to
further sublease all or any portion of the Premises except in accordance with
the terms of this Paragraph 23.

     (G) Tenant acknowledges and agrees that the restrictions, conditions and
limitations imposed by this Paragraph 23 on Tenant's ability to assign or
transfer this Lease or any interest herein, to sublet the Premises or any part
thereof, to transfer or assign any right or privilege appurtenant to the
Premises, or to allow any other person to occupy or use the Premises or any
portion thereof, are, for the purposes of California Civil Code Section 1951.4,
as amended from time to time, and for all other purposes, reasonable at the time
that the Lease was entered into, and shall be deemed to be reasonable at the
time that Tenant seeks to assign or transfer this Lease or any interest herein,
to sublet the Premises or any part thereof, to transfer or assign any right or
privilege appurtenant to the Premises, or to allow any other-person to occupy or
use the Premises or any portion thereof.

24.     TENANT'S DEFAULT

        The occurrence of any one of the following events shall constitute an
event of default on the part of Tenant ("Default"):

     (A) The vacation of the Premises for a period, in the aggregate, of
[...***...] or abandonment of the Premises by Tenant for a period of [...***...]
consecutive days or any vacation or abandonment of the Premises by Tenant which
would cause any insurance policy to be invalidated or otherwise lapse, or the
failure of Tenant to continuously operate Tenant's business in the Premises, in
each of the foregoing cases irrespective of whether or not Tenant is then in
monetary default under this Lease. Tenant agrees to notice and service of notice
as provided for in this Lease and waives any right to any other or further
notice or service of notice which Tenant may have under any statute or law now
or hereafter in effect;

     (B) Failure to pay any installment of Rent or any other monies due and
payable hereunder, said failure continuing for a period of three (3) days after
Landlord's notice of such failure;

     (C) A general assignment by Tenant or any guarantor or surety of Tenant's
obligations hereunder (collectively, "Guarantor") for the benefit of creditors;

     (D) The filing of a voluntary petition in bankruptcy by Tenant or any
Guarantor, the filing by Tenant or any Guarantor of a voluntary petition for an
arrangement, the filing by or against Tenant or any Guarantor of a petition,
voluntary or involuntary, for reorganization, or the filing 


*CONFIDENTIAL TREATMENT REQUESTED


                                      30.


<PAGE>   37
of an involuntary petition by the creditors of Tenant or any Guarantor, said
involuntary petition remaining undischarged for a period of sixty (60) days;

     (E) Receivership, attachment, or other judicial seizure of substantially
all of Tenant's assets on the Premises, such attachment or other seizure
remaining undismissed or undischarged for a period of sixty (60) days after the
levy thereof;

     (F) Death or disability of Tenant or any Guarantor, if Tenant or such
Guarantor is a natural person, or the failure by Tenant or any Guarantor to
maintain its legal existence, if Tenant or such Guarantor is a corporation,
partnership, limited liability company, trust or other legal entity;

     (G) Failure of Tenant to execute and deliver to Landlord any estoppel
certificate, subordination agreement, or lease amendment in the time periods and
manner required by Paragraphs 30 or 31 or 42;

     (H) An assignment or sublease, or attempted assignment or sublease, of this
Lease or the Premises by Tenant contrary to the provision of Paragraph 24,
unless such assignment or sublease is expressly conditioned upon Tenant having
received Landlord's consent thereto;

     (I) Failure of Tenant to restore the Security Deposit to the amount and
within the time period provided in Paragraph 7 above;

     (J) Failure in the performance of any of Tenant's covenants, agreements or
obligations hereunder (except those failures specified as events of Default in
subparagraphs (b), (1) or (m) above or any other subparagraphs of this Paragraph
25, which shall be governed by such other Paragraphs), which failure continues
for ten (10) days after written notice thereof from Landlord to Tenant, provided
that, if Tenant has exercised reasonable diligence to cure such failure and such
failure cannot be cured within such ten (10) day period despite reasonable
diligence, Tenant shall not be in default under this subparagraph so long as
Tenant thereafter diligently and continuously prosecutes the cure to completion
and actually completes such cure within a reasonable time after the giving of
the aforesaid written notice;

     (K) Chronic delinquency by Tenant in the payment of Rent, or any other
periodic payments required to be paid by Tenant under this Lease. "Chronic
delinquency" shall mean failure by Tenant to pay Rent, or any other periodic
payments required to be paid by Tenant under this Lease and Landlord's delivery
of written notice of such failure (i) for any three (3) months (consecutive or
nonconsecutive) during any period of twelve (12) months or (ii) for any six (6)
months (consecutive or nonconsecutive) during the Term. In the event of a
Chronic Delinquency, in addition to Landlord's other remedies for Default
provided in this Lease, at Landlord's option, Landlord shall have the right to
require that Rent be paid by Tenant quarterly, in advance;

     (L) Chronic overuse by Tenant or Tenant's Agents of the number of
undesignated parking spaces set forth in the Basic Lease Information. "Chronic
Overuse" shall mean use by Tenant or Tenant's Agents of a number of parking
spaces greater than the number of parking spaces set forth in the Basic Lease
Information more than three (3) times during any twelve (12) month period after
written notice by Landlord;


                                      31.


<PAGE>   38
     (M) Any insurance required to be maintained by Tenant pursuant to this
Lease shall be canceled or terminated or shall expire or be reduced or
materially changed, except as permitted in this Lease; and

     (N) Any failure by Tenant to discharge any lien or encumbrance placed on
the Project or any part thereof in violation of this Lease within ten (10) days
after the date such lien or encumbrance is filed or recorded against the Project
or any part thereof.

        Tenant agrees that any notice given by Landlord pursuant to Paragraph
25(j), (k) or (1) above shall satisfy the requirements for notice under
California Code of Civil Procedure Section 1161, and Landlord shall not be
required to give any additional notice in order to be entitled to commence an
unlawful detainer proceeding.

        Notwithstanding anything in this Paragraph 24 to the contrary, Tenant
may cure a Default under Paragraph 24(c), (d) or (f) above relating to the
Guarantor (or an event which with the giving of notice or the passing of time or
both, would constitute such a Default hereunder) ("Potential Default"), by
delivering to Landlord a Letter of Credit in accordance with Paragraph 4 of this
Lease within ten (10) days after written notice from Landlord of such Default or
Potential Default.

25.     LANDLORD'S REMEDIES

     (A) TERMINATION. In the event of any Default by Tenant, then in addition to
any other remedies available to Landlord at law or in equity and under this
Lease, Landlord shall have the immediate option to terminate this Lease and all
rights of Tenant hereunder by giving written notice of such intention to
terminate. In the event that Landlord shall elect to so terminate this Lease
then Landlord may recover from Tenant:

          (1) the worth at the time of award of any unpaid Rent and any other
sums due and payable which have been earned at the time of such termination;
plus

          (2) the worth at the time of award of the amount by which the unpaid
Rent and any other sums due and payable which would have been earned after
termination until the time of award exceeds the amount of such rental loss
Tenant proves could have been reasonably avoided; plus

          (3) the worth at the time of award of the amount by which the unpaid
Rent and any other sums due and payable for the balance of the term of this
Lease after the time of award exceeds the amount of such rental loss that Tenant
proves could be reasonably avoided; plus

          (4) 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 would be likely to result
therefrom, including, without limitation, (A) any costs or expenses incurred by
Landlord (1) in retaking possession of the Premises; (2) in maintaining,
repairing, preserving, restoring, replacing, cleaning, altering, remodeling or
rehabilitating the Premises or any affected portions of the Building or the
Project, including such actions undertaken in connection with the reletting or
attempted reletting of the Premises to a new tenant or tenants; (3) for leasing
commissions, advertising costs and other expenses of 


                                      32.


<PAGE>   39
reletting the Premises; or (4) in carrying the Premises, including taxes,
insurance premiums, utilities and security precautions; (B) any unearned
brokerage commissions paid in connection with this Lease; (c) reimbursement of
any previously waived or abated Base Rent or Additional Rent or any free rent or
reduced rental rate granted hereunder; and (D) any concession made or paid by
Landlord to the benefit of Tenant in consideration of this Lease including, but
not limited to, any moving allowances, contributions, payments or loans by
Landlord for tenant improvements or build-out allowances (including without
limitation, any unamortized portion of the Tenant Improvement Allowance (such
Tenant Improvement Allowance to be amortized over the Term in the manner
reasonably determined by Landlord), if any, and any outstanding balance
(principal and accrued interest) of the Tenant Improvement Loan, if any), or
assumptions by Landlord of any of Tenant's previous lease obligations; plus

          (5) such reasonable attorneys' fees incurred by Landlord as a result
of a Default, and costs in the event suit is filed by Landlord to enforce such
remedy; and plus

          (6) at Landlord's election, such other amounts in addition to or in
lieu of the foregoing as may be permitted from time to time by applicable law.

As used in subparagraphs (1) and (2) above, the "worth at the time of award" is
computed by allowing interest at an annual rate equal to [...***...] per annum
or the maximum rate permitted by law, whichever is less. As used in subparagraph
(3) above, the "worth at the time of award" is computed by discounting such
amount at the discount rate of the Federal Reserve Bank of San Francisco at the
time of award, plus [...***...]. Tenant waives redemption or relief from
forfeiture under California Code of Civil Procedure Sections 1174 and 1179, or
under any other pertinent present or future Law, in the event Tenant is evicted
or Landlord takes possession of the Premises by reason of any Default of Tenant
hereunder.

     (B) CONTINUATION OF LEASE. In the event of any Default by Tenant, then in
addition to any other remedies available to Landlord at law or in equity and
under this Lease, Landlord shall have the remedy described in California Civil
Code Section 1951.4 (Landlord may continue this Lease in effect after Tenant's
Default and abandonment and recover Rent as it becomes due, provided Tenant has
the right to sublet or assign, subject only to reasonable limitations). In
addition, Landlord shall not be liable in any way whatsoever for its failure or
refusal to relet the Premises. For purposes of this Paragraph 25(b), the
following acts by Landlord will not constitute the termination of Tenant's right
to possession of the Premises:

          (1) Acts of maintenance or preservation or efforts to relet the
Premises, including; but not limited to, alterations, remodeling, redecorating,
repairs, replacements and/or painting as Landlord shall consider advisable for
the purpose of reletting the Premises or any part thereof; or

          (2) The appointment of a receiver upon the initiative of Landlord to
protect Landlord's interest under this Lease or in the Premises.

     (C) RE-ENTRY. In the event of any Default by Tenant, Landlord shall also
have the right, with or without terminating this Lease, in compliance with
applicable law, to re-enter the 


*CONFIDENTIAL TREATMENT REQUESTED


                                      33.


<PAGE>   40
Premises and remove all persons and property from the Premises; such property
may be removed and stored in a public warehouse or elsewhere at the cost of and
for the account of Tenant.

     (D) RELETTING. In the event of the abandonment of the Premises by Tenant or
in the event that Landlord shall elect to re-enter as provided in Paragraph
25(c) or shall take possession of the Premises pursuant to legal proceeding or
pursuant to any notice provided by law, then if Landlord does not elect to
terminate this Lease as provided in Paragraph 25(a), Landlord may from time to
time, without terminating this Lease, relet the Premises or any part thereof for
such term or terms and at such rental or rentals and upon such other terms and
conditions as Landlord in its sole discretion may deem advisable with the right
to make alterations and repairs to the Premises in Landlord's sole discretion.
In the event that Landlord shall elect to so relet, then rentals received by
Landlord from such reletting shall be applied in the following order: (1) to
reasonable attorneys' fees incurred by Landlord as a result of a Default and
costs in the event suit is filed by Landlord to enforce such remedies; (2) to
the payment of any indebtedness other than Rent due hereunder from Tenant to
Landlord; (3) to the payment of any costs of such reletting; (4) to the payment
of the costs of any alterations and repairs to the Premises; (5) to the payment
of Rent due and unpaid hereunder; and (6) the residue, if any, shall be held by
Landlord and applied in payment of future Rent and other sums payable by Tenant
hereunder as the same may become due and payable hereunder. Should that portion
of such rentals received from such reletting during any month, which is applied
to the payment of Rent hereunder, be less than the Rent payable during the month
by Tenant hereunder, then Tenant shall pay such deficiency to Landlord. Such
deficiency shall be calculated and paid monthly. Tenant shall also pay to
Landlord, as soon as ascertained, any costs and expenses incurred by Landlord in
such reletting or in making such alterations and repairs not covered by the
rentals received from such reletting.

     (E) TERMINATION. No re-entry or taking of possession of the Premises by
Landlord pursuant to this Paragraph 25 shall be construed as an election to
terminate this Lease unless a written notice of such intention is given to
Tenant or unless the termination thereof is decreed by a court of competent
jurisdiction. Notwithstanding any reletting without termination by Landlord
because of any Default by Tenant, Landlord may at any time after such reletting
elect to terminate this Lease for any such Default.

     (F) CUMULATIVE REMEDIES. The remedies herein provided are not exclusive and
Landlord shall have any and all other remedies provided herein or by law or in
equity.

     (G) NO SURRENDER. No act or conduct of Landlord, whether consisting of the
acceptance of the keys to the Premises, or otherwise, shall be deemed to be or
constitute an acceptance of the surrender of the Premises by Tenant prior to the
expiration of the Term, and such acceptance by Landlord of surrender by Tenant
shall only flow from and must be evidenced by a written acknowledgment of
acceptance of surrender signed by Landlord. The surrender of this Lease by
Tenant, voluntarily or otherwise, shall not work a merger unless Landlord elects
in writing that such merger take place, but shall operate as an assignment to
Landlord of any and all existing subleases, or Landlord may, at its option,
elect in writing to treat such surrender as a merger terminating Tenant's estate
under this Lease, and thereupon Landlord may terminate any or all 


                                      34.


<PAGE>   41
such subleases by notifying the sublessee of its election so to do within
[...***...] days after such surrender.

26.     LANDLORD'S RIGHT TO PERFORM TENANT'S OBLIGATIONS

     (A) Without limiting the rights and remedies of Landlord contained in
Paragraph 25 above, if Tenant shall be in Default in the performance of any of
the terms, provisions, covenants or conditions to be performed or complied with
by Tenant pursuant to this Lease, then Landlord may at Landlord's option,
without any obligation to do so, and without notice to Tenant perform any such
term, provision, covenant, or condition, or make any such payment and Landlord
by reason of so doing shall not be liable or responsible for any loss or damage
thereby sustained by Tenant or anyone holding under or through Tenant or any of
Tenant's Agents, unless caused by Landlord's gross negligence or willful
misconduct.

Without limiting the rights of Landlord under Paragraph 25(a) above, Landlord
shall have the right at Landlord's option, without any obligation to do so, to
perform any of Tenant's covenants or obligations under this Lease without notice
to Tenant in the case of an emergency, as determined by Landlord in its sole and
absolute judgment, or if Landlord otherwise determines in its reasonable
discretion that such performance is necessary or desirable for the proper
management and operation of the Building or the Project or for the preservation
of the rights and interests or safety of other tenants of the Building or the
Project.

     (B) If Landlord performs any of Tenant's obligations hereunder in
accordance with this Paragraph 26, the full amount of the cost and expense
incurred or the payment so made or the amount of the loss so sustained shall
immediately be owing by Tenant to Landlord, and Tenant shall promptly pay to
Landlord upon demand, as Additional Rent, the full amount thereof with interest
thereon from the date of payment by Landlord at the lower of [...***...] per
annum, or (2) [...***...].

27.     ATTORNEY'S FEES

     (A) If either party hereto fails to perform any of its obligations under
this Lease or if any dispute arises between the parties hereto concerning the
meaning or interpretation of any provision of this Lease, then the defaulting
party or the party not prevailing in such dispute, as the case may be, shall pay
any and all costs and expenses incurred by the other party on account of such
default and/or in enforcing or establishing its rights hereunder, including,
without limitation, court costs and reasonable attorneys' fees and
disbursements. Any such attorneys' fees and other expenses incurred by either
party in enforcing a judgment in its favor under this Lease shall be recoverable
separately from and in addition to any other amount included in such judgment,
and such attorneys' fees obligation is intended to be severable from the other
provisions of this Lease and to survive and not be merged into any such
judgment.

     (B) Without limiting the generality of Paragraph 27(a) above, if Landlord
utilizes the services of an attorney for the purpose of collecting any Rent due
and unpaid by Tenant or in connection with any other breach of this Lease by
Tenant, Tenant agrees to pay Landlord 


*CONFIDENTIAL TREATMENT REQUESTED


                                      35.


<PAGE>   42

reasonable attorneys' fees as determined by Landlord for such services,
regardless of the fact that no legal action may be commenced or filed by
Landlord.

28.     TAXES

        Tenant shall be liable for and shall pay, prior to delinquency, all
taxes levied against Tenant's Property. If any Alteration installed by Tenant
pursuant to Paragraph 12 or any of Tenant's Property is assessed and taxed with
the Project or Building, Tenant shall pay such taxes to Landlord within ten (10)
days after delivery to Tenant of a statement therefor.

29.     EFFECT OF CONVEYANCE

        The term "Landlord" as used in this Lease means, from time to time, the
then current owner of the Building or the Project containing the Premises, so
that, in the event of any sale of the Building or the Project, Landlord shall be
and hereby is entirely freed and relieved of all covenants and obligations of
Landlord arising hereunder from and after the date of such transfer, and it
shall be deemed and construed, without further agreement between the parties and
the purchaser at any such sale, that the purchaser of the Building or the
Project has assumed and agreed to carry out any and all covenants and
obligations of Landlord hereunder.

30.     TENANT'S ESTOPPEL CERTIFICATE

        From time to time, upon written request of either party (the "Requesting
Party"), the other party (the "Responding Party") shall execute, acknowledge and
deliver to the Requesting Party or its designee, a written certificate stating
(a) the date this Lease was executed, the Commencement Date of the Term and the
date the Term expires; (b) the date Tenant entered into occupancy of the
Premises; (c) the amount of Rent and the date to which such Rent has been paid;
(d) that this Lease is in full force and effect and has not been assigned,
modified, supplemented or amended in any way (or, if assigned, modified,
supplemented or amended, specifying the date and terms of any agreement so
affecting this Lease); (e) that this Lease represents the entire agreement
between the parties with respect to Tenant's right to use and occupy the
Premises (or specifying such other agreements, if any); (f) that all obligations
under this Lease to be performed by the Requesting Party as of the date of such
certificate have been satisfied (or specifying those as to which the Responding
Party claims that the Requesting Party has yet to perform); (g) that all
required contributions by Landlord to Tenant on account of Tenant's improvements
have been received (or stating exceptions thereto); (h) that on such date there
exist no defenses or offsets that Tenant has against the enforcement of this
Lease by Landlord (or stating exceptions thereto); (i) that no Rent or other sum
payable by Tenant hereunder has been paid more than one (1) month in advance (or
stating exceptions thereto); (j) that a currently valid letter of credit and
security deposit have been deposited with Landlord, stating the original amount
thereof and any increases or decreases thereto; and (k) any other matters
evidencing the status of this Lease that may be required either by a lender
making a loan to Landlord to be secured by a deed of trust covering the Building
or the Project or by a purchaser of the Building or the Project or a purchase of
Tenant's stock or assets. Any such certificate delivered pursuant to this
Paragraph 30 may be relied upon by a prospective purchaser of Landlord's
interest or a mortgagee of Landlord's interest or assignee of any mortgage upon
Landlord's interest in the Premises. If the Responding Party shall fail to
provide such certificate 



                                      36.


<PAGE>   43
within ten (10) days of receipt by the Responding Party of a written request by
the Requesting Party as herein provided, such failure shall, at the Requesting
Perry's election, constitute a Default under this Lease.

31.     SUBORDINATION.

Landlord shall have the right to cause this Lease to be and remain subject and
subordinate to any and all mortgages, deeds of trust and ground leases, if any
("Encumbrances") that are now or may hereafter be executed covering the
Premises, or any renewals, modifications, consolidations, replacements or
extensions thereof, for the full amount of all advances made or to be made
thereunder and without regard to .the time or character of such advances,
together with interest thereon and subject to all the terms and provisions
thereof; provided only, and as an express condition precedent to such
subordination, that in the event of termination of any such ground lease or upon
the foreclosure of any such mortgage or deed of trust, so long as Tenant is not
in default, the holder thereof ("Holder") shall agree to recognize Tenant's
rights under this Lease as long as Tenant shall pay the Rent and observe and
perform all the provisions of this Lease to be observed and performed by Tenant.
Within [...***...] days after Landlord's written request, Tenant shall execute,
acknowledge and deliver any and all reasonable documents required by Landlord or
the Holder to effectuate such subordination. If Tenant fails to do so, such
failure shall constitute a Default by Tenant under this Lease. Notwithstanding
anything to the contrary set forth in this Paragraph 31, Tenant hereby attorns
and agrees to attorn to any person or entity purchasing or otherwise acquiring
the Premises at any sale or other proceeding or pursuant to the exercise of any
other rights, powers or remedies under such Encumbrance.

32.     ENVIRONMENTAL COVENANTS

     (A) Prior to executing this Lease, Tenant has completed, executed and
delivered to Landlord a Hazardous Materials Disclosure Certificate ("Initial
Disclosure Certificate"), a fully completed copy of which is attached hereto as
Exhibit F and incorporated herein by this reference. Tenant covenants,
represents and warrants to Landlord that the information on the Initial
Disclosure Certificate is, to the best of Tenant's knowledge, true and correct
and accurately describes the Hazardous Materials which will be manufactured,
treated, used or stored on or about the Premises by Tenant or Tenant's Agents.
[...***...] Tenant shall deliver to Landlord copies of any and all filings (a
"Filing") made after the Commencement Date with any state, local or federal
governmental agencies relating to Hazardous Materials used or to be used on or
about the Premises and Tenant shall promptly upon Landlord's request make
appropriate representatives of Tenant available to discuss with Landlord any
such Filing. Tenant shall make no use of Hazardous Materials on or about the
Premises except as described in the Initial Disclosure Certificate or an Updated
Disclosure Certificate, as required hereunder.

     (B) As used in this Lease, the term "Hazardous Materials" shall mean and
include any substance that is or contains (1) any "hazardous substance" as now
or hereafter defined in Section 101 (14) of the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980, as amended ("CERCLA") (42
U.S.C. Section 9601 et seq.) or any regulations promulgated under 


*CONFIDENTIAL TREATMENT REQUESTED


                                      37.


<PAGE>   44

CERCLA; (2) any "hazardous waste" as now or hereafter defined in the Resource
Conservation and Recovery Act, as amended ("RCRA") (42 U.S.C. Section 6901 et
seq.) or any regulations promulgated under RCRA; (3) any substance now or
hereafter regulated by the Toxic Substances Control Act, as amended ("TSCA") (15
U.S.C. Section 2601 et seq.) or any regulations promulgated under TSCA; (4)
petroleum, petroleum by-products, gasoline, diesel fuel, or other petroleum
hydrocarbons; (5) asbestos and asbestos-containing material, in any form,
whether friable or non-friable; (6) polychlorinated biphenyls; (7) lead and
lead-containing materials; or (8) any additional substance, material or waste
(A) the presence of which on or about the Premises (i) requires reporting,
investigation or remediation under any Environmental Laws (as hereinafter
defined), (ii) causes or threatens to cause a nuisance on the Premises or any
adjacent area or property or poses or threatens to pose a hazard to the health
or safety of persons on the Premises or any adjacent area or property, or (iii)
which, if it emanated or migrated from the Premises, could constitute a
trespass, or(B) which is now or is hereafter classified or considered to be
hazardous or toxic under any Environmental Laws.

     (C) As used in this Lease, the term "Environmental Laws" shall mean and
include (1) CERCLA, RCRA and TSCA; and (2) any other federal, state or local
laws, ordinances, statutes, codes, rules, regulations, orders or decrees now or
hereinafter in effect relating to (A) pollution, (B) the protection or
regulation of human health, natural resources or the environment, (c) the
treatment, storage or disposal of Hazardous Materials, or (D) the emission,
discharge, release or threatened release of Hazardous Materials into the
environment.

     (D) Tenant agrees that during its use and occupancy of the Premises it will
(1) not (A) permit Hazardous Materials to be present on or about the Premises
except in a manner and quantity necessary for the ordinary performance of
Tenant's business or (B) release, discharge or dispose of any Hazardous
Materials on, in, at, under, or emanating from, the Premises, the Building or
the Project; (2) comply with all Environmental Laws relating to Tenant's use of
Hazardous Materials in, on or about the Premises and not engage in or permit
Tenant's Agents to engage in any activity in, on or about the Premises in
violation of any Environmental Laws; and (3) immediately notify Landlord of (A)
any inquiry, test, investigation or enforcement proceeding by any governmental
agency or authority against Tenant, Landlord or the Premises, Building or
Project relating to any Hazardous Materials or under any Environmental Laws or
(B) the occurrence of any event or existence of any condition that would cause a
breach of any of the covenants set forth in this Paragraph 32.

     (E) If Tenant's use of Hazardous Materials on or about the Premises results
in a release, discharge or disposal of Hazardous Materials on, in, at, under, or
emanating from, the Premises, the Building or the Project, Tenant agrees to
investigate, clean up, remove or remediate such Hazardous Materials in full
compliance with (1) the requirements of (A) all Environmental Laws and (B) any
governmental agency or authority responsible for the enforcement of any
Environmental Laws; and (2) any additional requirements of Landlord that are
reasonably necessary to protect the value of the Premises, the Building or the
Project.

     (F) Upon reasonable notice to Tenant, Landlord may inspect the Premises and
surrounding areas for the purpose of determining whether there exists on or
about the Premises any Hazardous Material or other condition or activity that is
in violation of the requirements of this Lease or of any Environmental Laws.
Such inspections may include, but are not limited to, 


                                      38.


<PAGE>   45
entering upon the property adjacent to or surrounding the Premises with drill
rigs or other machinery for the purpose of obtaining laboratory samples.
Landlord shall not be limited in the number of such inspections during the Term
of this Lease but such inspections shall be reasonable in light of the
circumstances. In the event (1) such inspections reveal the presence of any such
Hazardous Material or other condition or activity caused by Tenant or its Agents
in violation of the requirements of this Lease or of any Environmental Laws, or
(2) Tenant or its Agents contribute or knowingly consent to the importation of
any Hazardous Materials in, on, under, through or about the Premises, the
Building or the Project or knowingly exacerbate the condition of or the
conditions caused by any Hazardous Materials in, on, under, through or about the
Premises, the Building or the Project, Tenant shall reimburse Landlord for the
cost of such inspections within ten (10) days of receipt of a written statement
therefor. Tenant will supply to Landlord such historical and operational
information regarding the Premises and surrounding areas as may be reasonably
requested to facilitate any such inspection and will make available for meetings
appropriate personnel having knowledge of such matters. Tenant agrees to give
Landlord at least sixty (60) days' prior notice of its intention to vacate the
Premises so that Landlord will have an opportunity to perform such an inspection
prior to such vacation. The right granted to Landlord herein to perform
inspections shall not create a duty on Landlord's part to inspect the Premises,
or liability on the part of Landlord for Tenant's use, storage, treatment or
disposal of Hazardous Materials, it being understood that Tenant shall be solely
responsible for all liability in connection therewith.

     (G) Landlord shall have the right, but not the obligation, prior or
subsequent to a Default, without in any way limiting Landlord's other rights and
remedies under this Lease, to enter upon the Premises, or to take such other
actions as it deems necessary or advisable, to investigate, clean up, remove or
remediate any Hazardous Materials or contamination by Hazardous Materials
present on, in, at, under, or emanating from, the Premises, the Building or the
Project in violation of Tenant's obligations under this Lease or under any
Environmental Laws. Notwithstanding any other provision of this Lease, Landlord
shall also have the right, at its election, in its own name or as Tenant's
agent, to negotiate, defend, approve and appeal, at Tenant's expense, any action
taken or order issued by any governmental agency or authority with regard to any
such Hazardous Materials or contamination by Hazardous Materials. All costs and
expenses paid or incurred by Landlord in the exercise of the rights set forth in
this Paragraph 32 shall be payable by Tenant upon demand.

     (H) Tenant shall surrender the Premises to Landlord upon the expiration or
earlier termination of this Lease free of debris, waste or Hazardous Materials
placed on, about or near the Premises by Tenant or Tenant's Agents, and in a
condition which complies with (i) all Environmental Laws relating to Hazardous
Materials placed on, about or near the Premises by Tenant or Tenant's Agents and
(ii) any additional requirements of Landlord that are reasonably necessary to
protect the value of the Premises, the Building or the Project, including,
without limitation, the obtaining of any closure permits or other governmental
permits or approvals related to Tenant' s use of Hazardous Materials in or about
the Premises. Tenant's obligations and liabilities pursuant to the provisions of
this Paragraph 32 shall survive the expiration or earlier termination of this
Lease. If it is determined by Landlord that the condition of all or any portion
of the Premises, the Building, and/or the Project is not in compliance with the
provisions of this Lease with respect to Hazardous Materials, including, without
limitation, all Environmental Laws, at the expiration or earlier termination of
this Lease, then at Landlord's 


                                      39.


<PAGE>   46
sole option, Landlord may require Tenant to hold over possession of the Premises
until Tenant can surrender the Premises to Landlord in the condition in which
the Premises existed as of the Commencement Date and prior to the appearance of
such Hazardous Materials which Tenant or Tenant's Agents caused to be present
except for normal wear and tear, including, without limitation, the conduct or
performance of any closures as required by any Environmental Laws. The burden of
proof hereunder shall be upon Tenant. For purposes hereof, the term "normal wear
and tear" shall not include any deterioration in the condition or diminution of
the value of any portion of the Premises, the Building, and/or the Project in
any manner whatsoever related to directly, or indirectly, Hazardous Materials.
Any such holdover by Tenant will be with Landlord's consent, will not be
terminable by Tenant in any event or circumstance and will otherwise be subject
to the provisions of Paragraph 35 of this Lease.

     (I) Tenant agrees to indemnify and hold harmless Landlord from and against
any and all claims, losses (including, without limitation, loss in value of the
Premises, the Building or the Project, liabilities and expenses (including
attorney's fees)) sustained by Landlord attributable to (1) any Hazardous
Materials placed on or about the Premises, the Building or the Project by Tenant
or Tenant's Agents, or (2) Tenant's breach of any provision of this Paragraph
32.

     (J) Landlord agrees to indemnify and hold harmless Tenant from and against
any and all claims, losses (including, without limitation, liabilities and
expenses (including attorneys' fees)) actually sustained by Tenant attributable
to any Hazardous Materials placed on or about the Premises, the Building or the
Project by Landlord or Landlord's Agents, but specifically excluding any other
third parties.

     (K) The provisions of this Paragraph 32 shall survive the expiration or 
earlier termination of this Lease.

33.     NOTICES.

        All notices and demands which are required or may be permitted to be
given to either party by the other hereunder shall be in writing and shall be
sent by United States mail, postage prepaid, certified, or by personal delivery
or overnight courier, addressed to the addressee at Tenant's Address or
Landlord's Address as specified in the Basic Lease Information, or to such other
place as either party may from time to time designate in a notice to the other
party given as provided herein. Copies of all notices and demands given to
Landlord shall additionally be sent to Landlord's property manager at the
address specified in the Basic Lease Information or at such other address as
Landlord may specify in writing from time to time. Notice shall be deemed given
upon actual receipt (or attempted delivery if delivery is refused), if
personally delivered, or one (I) business day following deposit with a reputable
overnight courier that provides a receipt, or on the third (3rd) day following
deposit in the United States mail in the manner described above.

34.     WAIVER.

        The waiver of any breach of any term, covenant or condition of this
Lease shall not be deemed to be a waiver of such term, covenant or condition or
of any subsequent breach of the same or any other term, covenant or condition
herein contained. The subsequent acceptance of 


                                      40.


<PAGE>   47
Rent by Landlord shall not be deemed to be a waiver of any preceding breach by
Tenant, other than the failure of Tenant to pay the particular rental so
accepted, regardless of Landlord's knowledge of such preceding breach at the
time of acceptance of such Rent. No delay or omission in the exercise of any
right or remedy of Landlord in regard to any Default by Tenant shall impair such
a right or remedy or be construed as a waiver. Any waiver by Landlord of any
Default must be in writing and shall not be a waiver of any other Default
concerning the same or any other provisions of this Lease.

35.     HOLDING OVER.

        Any holding over after the expiration of the Term, without the express
written consent of Landlord, shall constitute a Default and, without limiting
Landlord's remedies provided in this Lease, such holding over shall be construed
to be a tenancy at sufferance, at a rental rate of [...***...] of the Base Rent
last due in this Lease, plus Additional Rent, and shall otherwise be on the
terms and conditions herein specified, so far as applicable; provided, however,
in no event shall any renewal or expansion option or other similar right or
option contained in this Lease be deemed applicable to any such tenancy at
sufferance. If the Premises are not surrendered at the end of the Term or sooner
termination of this Lease, and in accordance with the provisions of Paragraphs
11 and 32(h), Tenant shall indemnify, defend and hold Landlord harmless from and
against any and all loss or liability resulting from delay by Tenant in so
surrendering the Premises including, without limitation, any loss or liability
resulting from any claim against Landlord made by any succeeding tenant or
prospective tenant caused by such delay and losses to Landlord due to lost
opportunities to lease any portion of the Premises to any such succeeding tenant
or prospective tenant, together with, in each case, actual attorneys' fees and
costs.

36.     SUCCESSORS AND ASSIGNS.

     (A) The terms, covenants and conditions of this Lease shall, subject to the
provisions as to assignment, apply to and bind the heirs, successors, executors,
administrators and assigns of all of the parties hereto. If Tenant shall consist
of more than one entity or person, the obligations of Tenant under this Lease
shall be joint and several.

     (B) Notwithstanding anything in this Lease to the contrary, Landlord shall
have the right to sell, transfer or otherwise convey, either separately or
jointly, its interest in the Building and/or Expansion Land and/or Expansion
Building, and all of Landlord's related rights hereunder, to any Person,
provided that the original Landlord hereunder retains the obligation to
construct and deliver the Building and, if Tenant exercises the Expansion
Option, the Expansion Building, in accordance with the terms hereof. By way of
example only (and without limiting Landlord's rights under this Paragraph
36(b)), subject to compliance with applicable zoning and subdivision laws,
Landlord shall have the right to convey its interest in the Building and retain
its interest in and rights and obligations hereunder with respect to the
Expansion Land and/or the Expansion Building. Tenant agrees to cooperate with
Landlord at Landlord's request and at Landlord's sole cost and expense (except
as limited below) and to enter into such substitute or replacement lease and
option documents (the "Substitute Lease Documents") as Landlord shall 


*CONFIDENTIAL TREATMENT REQUESTED


                                      41.


<PAGE>   48
reasonably request to effectuate the intent of this subparagraph 36(b),
(including any provisions relating to payment of the Carry Costs, as hereinafter
defined, to the original Landlord), provided that the obligations of Tenant
under this Lease shall not be increased nor shall Tenant's rights under this
Lease be diminished as a result of the execution and delivery of such Substitute
Lease Documents, and provided further that Landlord shall pay Tenant's
reasonable legal fees incurred in connection with such Substitute Lease
Documents.

37.     TIME.

        Time is of the essence of this Lease and each and every term, condition
and provision herein.

38.     BROKERS.

Landlord and Tenant each represents and warrants to the other that neither it
nor its officers or agents nor anyone acting on its behalf has dealt with any
real estate broker except the Broker(s) specified in the Basic Lease Information
in the negotiating or making of this Lease, and each party agrees to indemnify
and hold harmless the other from any claim or claims, and costs and expenses,
including attorneys' fees, incurred by the indemnified party in conjunction with
any such claim or claims of any other broker or brokers to a commission in
connection with this Lease as a result of the actions of the indemnifying party.
Landlord shall pay the brokerage commissions due to the Brokers listed in the
Basic Lease Information.

39.     LIMITATION OF LIABILITY.

        Tenant agrees that, in the event of any default or breach by Landlord
with respect to any of the terms of the Lease to be observed and performed by
Landlord or with respect to the enforcement of an indemnity obligation of
Landlord under this Lease (1) Tenant shall look solely to the then-current
landlord's interest in the Building for the satisfaction of such indemnity
obligation of Landlord or for satisfaction of Tenant's remedies for the
collection of a judgment (or other judicial process) requiring the payment of
money by Landlord; (2) no other property or assets of Landlord, its partners,
shareholders, officers, directors, employees, investment advisors, or any
successor in interest of any of them (collectively, the "Landlord Parties")
shall be subject to levy, execution or other enforcement procedure for the
satisfaction of Tenant's remedies; (3) no personal liability shall at any time
be asserted or enforceable against the Landlord Parties; and (4) no judgment
will be taken against the Landlord Parties (except for a judgment against
Landlord which is enforceable only to the extent of Landlord's interest in the
Building). The provisions of this Paragraph shall apply only to the Landlord and
the parties herein described, and shall not be for the benefit of any insurer
nor any other third party.

40.     FINANCIAL STATEMENTS.

        Within [...***...] days after Landlord's request, Tenant shall deliver
to Landlord the then current financial statements of Tenant (including interim
periods following the end of the last fiscal year for which annual statements
are available), prepared or compiled by a certified public 


*CONFIDENTIAL TREATMENT REQUESTED


                                      42.


<PAGE>   49
accountant, including a balance sheet and profit and loss statement for the most
recent prior year, all prepared in accordance with generally accepted accounting
principles consistently applied.

41.     RULES AND REGULATIONS.

        Tenant agrees to comply with such reasonable rules and regulations as
Landlord may adopt from time to time for the orderly and proper operation of the
Building and the Project. Such rules may include but shall not be limited to the
following: (a) restriction of employee parking to a limited, designated area or
areas; and (b) regulation of the removal, storage and disposal of Tenant's
refuse and other rubbish at the sole cost and expense of Tenant. The then
current rules and regulations shall be binding upon Tenant upon delivery of a
copy of them to Tenant. Landlord shall not be responsible to Tenant for the
failure of any other person to observe and abide by any of said rules and
regulations; provided however, Landlord shall enforce such rules and regulation
in a non-discriminatory manner. Landlord's current rules and regulations are
attached to this Lease as Exhibit E.

42.     MORTGAGEE PROTECTION.

     (A) MODIFICATIONS FOR LENDER. If, in connection with obtaining financing
for the Project or any portion thereof, Landlord's lender shall request
reasonable modifications to this Lease as a condition to such financing, Tenant
shall not unreasonably withhold, delay or defer its consent to such
modifications, provided such modifications do not materially adversely affect
Tenant's rights or increase Tenant's obligations under this Lease.

     (B) RIGHTS TO CURE. Tenant agrees to give to any trust deed or mortgage
holder ("Holder"), by registered mail, at the same time as it is given to
Landlord, a copy of any notice of default given to Landlord, provided that prior
to such notice Tenant has been notified, in writing, (by way of notice of
assignment of rents and leases, or otherwise) of the address of such Holder.
Tenant further agrees that if Landlord shall have failed to cure such default
within the time provided for in this Lease, then the Holder shall have an
additional [...***...] days after expiration of such period, or after receipt of
such notice from Tenant (if such notice to the Holder is required by this
Paragraph 42(b)), whichever shall last occur within which to cure such default
or if such default cannot be cured within that time, then such additional time
as may be necessary if within such [...***...] days, any Holder has commenced
and is diligently pursuing the remedies necessary to cure such default
(including but not limited to commencement of foreclosure proceedings, if
necessary to effect such cure), in which event this Lease shall not be
terminated.

43.     ENTIRE AGREEMENT.

        This Lease, including the Exhibits and any Addenda attached hereto,
which are hereby incorporated herein by this reference, contains the entire
agreement of the parties hereto, and no representations, inducements, promises
or agreements, oral or otherwise, between the parties, not embodied herein or
therein, shall be of any force and effect.


*CONFIDENTIAL TREATMENT REQUESTED


                                      43.


<PAGE>   50
44.     INTEREST.

        Any installment of Rent and any other sum due from Tenant under this
Lease which is not received by Landlord when due shall bear interest from the
date such payment was originally due under this Lease until paid at an annual
rate equal to the maximum rate of interest permitted by law; provided, however,
Landlord hereby waives its right to collect interest on the first two (2) such
sums not paid to Landlord as required hereunder. Payment of such interest shall
not excuse or cure any Default by Tenant. In addition, Tenant shall pay all
costs and reasonable attorneys' fees incurred by Landlord in collection of such
amounts.

45.     INTERPRETATION.

This Lease shall be construed and interpreted in accordance with the laws of the
State of California. The parties acknowledge and agree that no rule of
construction to the effect that any ambiguities are to be resolved against the
drafting party shall be employed in the interpretation of this Lease, including
the Exhibits and any Addenda attached hereto. All captions in this Lease are for
reference only and shall not be used in the interpretation of this Lease.
Whenever required by the context of this Lease, the singular shall include the
plural, the masculine shall include the feminine, and vice versa. If any
provision of this Lease shall be determined to be illegal or unenforceable, such
determination shall not affect any other provision of this Lease and all such
other provisions shall remain in full force and effect. As used herein, the term
"gross negligence" shall mean any action or inaction taken with a reckless
disregard for the consequences. Unless otherwise specifically stated herein to
the contrary, Landlord's consent may be given or withheld in Landlord's sole and
absolute discretion.

46.     REPRESENTATIONS AND WARRANTIES.

     (A) OF TENANT. Tenant hereby makes the following representations and
warranties, each of which is material and being relied upon by Landlord, is true
in all respects as of the date of this Lease, and shall survive the expiration
or termination of the Lease.

          (1) If Tenant is an entity, Tenant is duly organized, validly existing
and in good standing under the laws of the state of its organization and the
persons executing this Lease on behalf of Tenant have the full right and
authority to execute this Lease on behalf of Tenant and to bind Tenant without
the consent or approval of any other person or entity. Tenant has full power,
capacity, authority and legal right to execute and deliver this Lease and to
perform all of its obligations hereunder. This Lease is a legal, valid and
binding obligation of Tenant, enforceable in accordance with its terms.

          (2) Tenant has not (i) made a general assignment for the benefit of
creditors, (ii) filed any voluntary petition in bankruptcy or suffered the
filing of an involuntary petition by any creditors, (iii) suffered the
appointment of a receiver to take possession of all or substantially all of its
assets, (iv) suffered the attachment or other judicial seizure of all or
substantially all of its assets, (v) admitted in writing its inability to pay
its debts as they come due, or (vi) made an offer of settlement, extension or
composition to its creditors generally.


                                      44.


<PAGE>   51
     (B) OF LANDLORD. Landlord hereby makes the following representations and
warranties, each of which is material and being relied upon by Tenant, is true
in all respects as of the date of this Lease, and shall survive the expiration
or termination of the Lease.

          (1) If Landlord is an entity, Landlord is duly organized, validly
existing and in good standing under the laws of the state of its organization
and the persons executing this Lease on behalf of Landlord have the full right
and authority to execute this Lease on behalf of Landlord and to bind Landlord
without the consent or approval of any other person or entity. Landlord has full
power, capacity, authority and legal right to execute and deliver this Lease and
to perform all of its obligations hereunder. This Lease is a legal, valid and
binding obligation of Landlord, enforceable in accordance with its terms.

Landlord has not (i) made a general assignment for the benefit of creditors,
(ii) filed any voluntary petition in bankruptcy or suffered the filing of an
involuntary petition by any creditors, (iii) suffered the appointment of a
receiver to take possession of all or substantially all of its assets, (iv)
suffered the attachment or other judicial seizure of all or substantially all of
its assets, (v) admitted in writing its inability to pay its debts as they come
due, or (vi) made an offer of settlement, extension or composition to its
creditors generally.

47.     SECURITY.

     (A) Tenant acknowledges and agrees that, while Landlord may engage security
personnel to patrol the Building or the Project, Landlord is not providing any
security services with respect to the Premises, the Building or the Project and
that Landlord shall not be liable to Tenant for, and Tenant waives any claim
against Landlord with respect to, any loss by theft or any other damage suffered
or incurred by Tenant in connection with any unauthorized entry into the
Premises or any other breach of security with respect to the Premises, the
Building or the Project.

     (B) Tenant hereby agrees to the exercise by Landlord and Landlord's Agents,
within their sole discretion, of such security measures as, but not limited to,
the evacuation of the Premises, the Building or the Project for cause, suspected
cause or for drill purposes, the denial of any access to the Premises, the
Building or the Project and other similarly related actions that it deems
necessary to prevent any threat of property damage or bodily injury. The
exercise of such security measures by Landlord and Landlord's Agents, and the
resulting interruption of service and cessation of Tenant's business, if any,
shall not be deemed an eviction or disturbance of Tenant's use and possession of
the Premises, or any part thereof, or render Landlord or Landlord's Agents
liable to Tenant for any resulting damages, unless caused by the gross
negligence or willful misconduct of Landlord, or relieve Tenant from Tenant's
obligations under this Lease.

48.     JURY TRIAL WAIVER.

        Tenant hereby waives any right to trial by jury with respect to any
action or proceeding (i) brought by Landlord, Tenant or any other party,
relating to (A) this Lease and/or any understandings or prior dealings between
the parties hereto, or (B) the Premises, the Building or the Project or any part
thereof, or (ii) to which Landlord is a party. Tenant hereby agrees that 


                                      45.


<PAGE>   52
this Lease constitutes a written consent to waiver of trial by jury pursuant to
the provisions of California Code of Civil Procedure Section 631.

49.     OPTION TO RENEW.

        Tenant shall have two (2) options (each a "Renewal Option") to extend
the Term of this Lease with respect to either the Building or the Expansion
Space, or both, each for a [...***...] year extended term (the "Renewal Term").
If Tenant has exercised the Expansion Option set forth in Paragraph 52 below,
Tenant may exercise the Renewal Option with respect to all of the original
Premises and/or the Expansion Space; provided however, as a condition to
exercising such Renewal Option, Tenant must be in possession of at least
[...***...] of the square footage of the building for which Tenant desires to
exercise the Renewal Option. Each Renewal Option shall be effective only if
Tenant is not in Default under this Lease, nor has any event occurred which with
the giving of notice or the passage of time, or both, would constitute a Default
hereunder, either at the time of exercise of the Renewal Option or the time of
commencement of the Renewal Term. If Tenant exercises the first Renewal Option
in accordance herewith, the first Renewal Term shall commence on the day
following the last day of the initial Term and end on the day preceding the
[...***...] anniversary thereof. If Tenant exercises the second Renewal Option,
the second Renewal Term shall commence on the day following the last day of the
first Renewal Term and end on the day preceding the [...***...] anniversary
thereof. The second Renewal Option may not be exercised unless Tenant has
previously exercised the first Renewal Option. Each Renewal Term, if properly
exercised, shall be upon the same terms and conditions as the Lease except for
Base Rent (which shall be determined as provided in the following provisions of
this Paragraph) and the size of the Premises (which shall be determined based
upon the square footage of the space subject to the Renewal Notice). The Renewal
Option shall be personal to Tenant and any transferee of a Permitted Transfer
and shall not be assignable or otherwise transferable to any other permitted
assignee, subtenant or other third parties and there shall be no further Renewal
Option beyond the expiration of the second Renewal Term. In order to exercise a
Renewal Option, Tenant shall give written notice to Landlord of Tenant's
exercise of such election ("Tenant's Notice") at least [...***...] prior to
expiration of the then current Term and if such notice is not so given, the
Renewal Option shall lapse; the Tenant hereby expressly acknowledges and agrees
that time is of the essence for purposes of notice of exercise of a Renewal
Option and that Tenant's failure to do so by said date will relieve Landlord of
any obligation under this Paragraph. If Tenant gives such notice within the time
prescribed, Landlord and Tenant shall be deemed to have entered into an
extension of this Lease with respect to the entirety of the Premises for a
[...***...] extended term on the terms and conditions set forth herein.

        The monthly Base Rent payable during any Renewal Term shall be an mount
equal to [...***...]. "Fair Market Rent" shall mean the rate being charged for
comparable Office/R&D space in the Northern Peninsula market area (excluding the
City of San Francisco), taking into consideration: tenant credit, tenant
improvements or allowances provided or to be provided and leasing commissions
but excluding tenant improvements paid for by Tenant. Landlord and Tenant shall
meet and attempt in good faith to mutually determine Fair Market Rent for the


*CONFIDENTIAL TREATMENT REQUESTED


                                      46.


<PAGE>   53
purposes of the foregoing. If the parties have not reached agreement on Fair
Market Rent by the date that is thirty (30) days after Tenant's Notice, each
party shall appoint an appraiser and shall give to the other party the identity
of the appraiser no later than the date that is forty (40) days after the
Tenant's Notice. If either party fails to appoint an appraiser by the date that
is forty (40) days after Tenant's Notice, the sole appraiser appointed, if any,
shall determine the Fair Market Rent. If two appraisers are appointed, they
shall immediately meet and attempt to agree upon such Fair Market Rent. If the
appraisers cannot reach agreement on the Fair Market Rent by the date that is
sixty (60) days after Tenant's Notice, each appraiser shall submit a
determination of Fair Market Rent to Landlord and Tenant. If the determinations
of Fair Market Rent made by these two appraisers vary by [...***...] or less,
the Fair Market Rent shall be the average or, the two determinations. If the
determinations vary by more than [...***...], the two appraisers shall within
[...***...] after submission of their determinations, appoint a third appraiser.
If the two appraisers shall be unable to agree on the selection of a third
appraiser within the [...***...], then either Tenant or Landlord may request
such appointment by petitioning the presiding judge of the Superior Court in and
for the County of San Mateo. Such third appraiser shall, within thirty (30) days
after appointment, make a determination of the Fair Market Rent and submit such
determination to Landlord and Tenant. The Fair Market Rent shall be the
determination of Fair Market Rent submitted by the original two appraisers that
is closer to the Fair Market Rent determination of the third appraiser. If the
third appraiser's determination is exactly between the Fair Market Rent
determination of the original two appraisers, then Fair Market Rent shall be the
average of the original two determinations. For purposes of this Paragraph,
"appraiser" shall mean a licensed commercial real estate broker or MAI
designated appraiser with not less than 5 years of full-time commercial
appraisal or brokerage experience in the Northern Peninsula market area. Each
party shall bear the fees and costs incurred by each party's appraiser in
connection with the determination of Fair Market Rent and all fees and costs
incurred by the third appraiser, if any, in connection with the determination of
Fair Market Rent shall be shared equally by Landlord and Tenant. If the
determination of Fair Market Rent has not been made by the expiration of the
then expiring Term, Tenant shall (i) continue to pay monthly Base Rent at the
monthly Base Rent for the last month of the Term (the "Arbitration Period Base
Rent") as well as any additional rent due under the Lease and (ii) pay to
Landlord, or receive as a refund from Landlord, as applicable, on the first day
of the month after the determination of Fair Market Rent is made, an amount, if
any, equal to the difference between the Arbitration Period Base Rent that was
paid to Landlord and the monthly Base Rent for the Renewal Term that should have
been paid to Landlord as the monthly Base Rent for the Renewal Term as
determined hereunder.

50.     RIGHT OF FIRST NEGOTIATION.

        Provided Tenant is not then in Default hereunder, Landlord shall notify
Tenant of the availability of any existing rentable space available within the
Project during the Term, (the "Negotiation Space"). Landlord agrees to review
and negotiate in good faith with Tenant any proposals submitted by Tenant with
respect to leasing the Negotiation Space prior to entering into any final lease
agreement for the Negotiation Space with third parties. Tenant's rights under
this Paragraph are subject and subordinate to any extension or expansion options
of other tenants 


*CONFIDENTIAL TREATMENT REQUESTED


                                      47.


<PAGE>   54
of the Project, whether now existing or hereafter granted. If Landlord and
Tenant are unable to execute a final lease agreement for the Negotiation Space
within 20 days of Landlord's notice to Tenant of the availability of the
Negotiation Space, Landlord shall have no further obligation to Tenant under
this Paragraph and shall be free to lease the space to any third parties. Tenant
hereby expressly acknowledges and agrees that time is of the essence for
purposes of this Paragraph. Notwithstanding anything in this Paragraph to the
contrary, Landlord shall have no obligation to lease to Tenant and Tenant shall
have no obligation to lease from Landlord the Negotiation Space and as such,
each party may act in its sole and absolute discretion in connection with this
Paragraph.

51.     RIGHT OF FIRST OFFER.

        If subsequent to full execution of this Lease, Landlord desires to sell
the Building and/or, if Tenant has exercised the Expansion Option, the Expansion
Building, Landlord shall notify Tenant in writing of such intent to sell (the
"Offer Notice"); provided however, Landlord shall not be required to provide
Tenant with the Offer Notice with respect to the Building or Expansion Building
if Landlord has previously terminated this Lease with respect to, or recaptured,
all or any portion of the Premises or the Expansion Space, respectively.
Tenant's right to receive the Offer Notice shall further be effective only if
Tenant is not in Default under this Lease, nor has any event occurred which with
the giving of notice or the passage of time, or both, would constitute a Default
hereunder. In the event Tenant desires to purchase the Building and/or the
Expansion Building, Tenant shall notify Landlord in writing of its election to
purchase the Building and/or the Expansion Building (the "Election Notice")
within thirty (30) days following Tenant's receipt of the Offer Notice. In the
event Tenant timely delivers the Election Notice to Landlord, the parties shall
thereafter execute a purchase and sale agreement (the "Purchase and Sale
Agreement") reasonably acceptable to both Landlord and Tenant with the purchase
price of the Building and/or the Expansion Building equal to the quotient of the
Net Operating Income (as defined below) of the Building and/or the Expansion
Building divided by [...***...] and with a closing to be held on or before the
date that is one hundred and eighty (180) days after delivery of the Offer
Notice. If Tenant fails to deliver an Election Notice within the 30-day time
period, or if Tenant has not executed the Purchase and Sale Agreement within
thirty (30) days after the date of Landlord's receipt of the Election Notice,
Tenant's right to purchase the Building and/or the Expansion Building hereunder
shall automatically terminate and be of no further force and effect with respect
to Landlord or any subsequent purchaser and Landlord shall thereafter have the
right to sell the Building and/or the Expansion Building at anytime to any third
party. Tenant hereby expressly acknowledges and agrees that time is of the
essence for purposes of the Election Notice and that Tenant's failure to deliver
such Election Notice as specified herein will relieve Landlord of any obligation
under this Paragraph. As used herein, Net Operating Income shall mean the Base
Kent due under the Lease with respect to the Building or the Expansion Building,
as applicable, for the (12) full calendar months following the Offer Notice.
Notwithstanding anything in this Paragraph to the contrary, this Paragraph shall
be inapplicable to, and Landlord shall have no obligation to provide an Offer
Notice to Tenant in connection with any sale or proposed sale of the Building
and/or the Expansion Building to any Person (as defined below) who is the owner
of at least a fifty-one percent (51%) legal or 


*CONFIDENTIAL TREATMENT REQUESTED


                                      48.


<PAGE>   55
beneficial interest and holder of a controlling interest in Landlord as of the
date of this Lease or at anytime in the future. As used herein "Person" shall
mean any natural person, corporation, firm, association or other entity, whether
acting in an individual, fiduciary or other capacity. Tenant's rights under this
Paragraph 51 shall survive Landlord's transfer to such Person.

52.     RIGHT TO EXPAND.

     (A) Tenant shall have one (1) option to expand (the "Expansion Option") the
Premises to include an approximately [...***...] square feet Building (the
"Expansion Space") to be constructed in the Project in the area shown on the
attached Exhibit G (the "Expansion Land"). The Expansion Option shall be
effective only if Tenant is not in Default under this Lease, nor has any event
occurred which with the giving of notice or the passage of time, or both, would
constitute a Default hereunder, either at the time of exercise of the Expansion
Option or the time of delivery of the Expansion Space. The Expansion Option
shall be personal to Tenant and any transferee of a Permitted Transfer and shall
not be assignable or otherwise transferable to any other permitted assignee,
subtenant or other third parties. In order to exercise the Expansion Option,
Tenant shall give written notice to Landlord (the "Expansion Notice") on or
before the date (the "Final Expansion Notice Date") that is the last day of the
first Lease Year. If the Expansion Notice is not so given, the Expansion Option
shall, except as provided in (b) below, automatically lapse; Tenant hereby
expressly acknowledges and agrees that time is of the essence for purposes of
delivering the Expansion Notice and that Tenant's failure to do so by the Final
Expansion Notice Date will relieve Landlord of any obligation under this
Paragraph 52.

     (B) Notwithstanding the terms of Paragraph 52(a) above, Tenant shall have
the right to extend the Final Expansion Notice Date to the last day of the
second Lease Year, provided that, on or before the expiration of the first Lease
Year Tenant delivers written notice of such election to Landlord (the "Extension
Notice"). If the Extension Notice is not so given, the Expansion Option shall
automatically lapse; Tenant hereby expressly acknowledges and agrees that time
is of the essence for purposes of delivering the Extension Notice and that
Tenant's failure to do so by said date will relieve Landlord of any obligation
under this Paragraph 52. If Tenant delivers the Extension Notice in a timely
manner as provided herein, Tenant shall have until the end of the second Lease
Year, (the "Extended Expansion Notice Date") to exercise the Expansion Option by
delivering an Expansion Notice to Landlord. If Tenant provides an Extension
Notice to Landlord and thereafter fails to exercise the Expansion Option in
accordance with this Paragraph 52(b), the monthly Base Rent then payable under
this Lease shall be increased by [...***...] per square foot and such increase
Base Rent shall thereafter be increased by [...***...] of the Monthly Base Rent
for the preceding Lease Year. By way of example, the monthly Base Rent payable
hereunder on a square footage basis during the [...***...] Lease Year shall be
adjusted to equal [...***...] which amount equals (i) the monthly Base Rent for
the [...***...] Lease Year, plus (ii) [...***...] per square foot and therefore,
the monthly Base Rent for the [...***...] Lease Year shall be [...***...].

     (C) The Expansion Notice shall specify the date Tenant desires to occupy
the Expansion Space (the "Requested Delivery Date"). The Requested Delivery Date
shall be no earlier than 


*CONFIDENTIAL TREATMENT REQUESTED


                                      49.


<PAGE>   56
[...***...] after the Commencement Date. Upon delivery of the Expansion Notice
and as a condition precedent to the effectiveness thereof, Tenant shall (i)
increase the Security Deposit under this Lease by [...***...] to a total of
[...***...], and (ii) provide Landlord with detailed financial statements and
other information reasonably acceptable to Landlord demonstrating that, as of
the date of the Expansion Notice, Tenant has cash and cash equivalents, as
defined in Paragraph 4 above, greater than [...***...] and a current ratio of
[...***...] or greater. As used in this Paragraph, "current ratio shall mean the
number obtained by dividing Tenant's current assets by current liabilities, as
such amounts are shown on Tenant's then most recent quarterly filing (Form 1
O-Q) with the Securities and Exchange Commission. Notwithstanding the condition
in (ii) above, the Expansion Notice shall be effective if Tenant delivers to
Landlord, as additional security for the full and faithful performance of
Tenant's covenants and obligations under this Lease, a letter of credit, in the
form and subject to the terms and conditions set forth in Paragraph 4 above, in
the amount of [...***...]. Notwithstanding the terms of Paragraph 4, during the
period from the Expansion Space Commencement Date through the sixth Lease Year,
the amount of such letter of credit shall be reduced by [...***...] on the last
day of each such Lease Year. During the period from the seventh Lease Year
through the Expiration Date, the amount of the letter of credit shall be reduced
by [...***...] on the last day of each such Lease Year.

     (D) Upon the Expansion Space Commencement Date (as defined in Exhibit B
hereto), the Lease shall be deemed amended such that the definition of Premises
shall include the Expansion Space and the definition of Building shall include
the newly constructed building in which the Expansion Space is located (the
"Expansion Building"). Tenant's occupancy of the Expansion Space shall be
subject to all of the terms and conditions of this Lease except as specifically
provided in Paragraph 52(f) below. Without limiting the generality of the
foregoing, Monthly Base Rent shall be due for the Expansion Space at the same
rate per square foot as then being charged for the original Premises (such
amount being determined by dividing the Monthly Base Rent by the original
Premises square footage) and shall be subject to the same adjustments as set
forth in the Lease, and Tenant's Proportionate Share(s) shall be adjusted to
include the addition of the Expansion Space, provided that any monetary
limitation on Expenses set forth in any provision of Paragraph 4 shall apply
separately to each building constituting a part of the Premises hereunder,
except that the [...***...] monetary limitation in Paragraph 4(b)(o) shall
remain at [...***...]. If, for any reason whatsoever, the Expansion Space
Commencement Date does not occur on or before the Requested Delivery Date, the
Expansion Option shall not be void or voidable, nor shall Landlord, or
Landlord's Agents, be liable to Tenant for any loss or damage resulting
therefrom. Tenant shall not be liable for Rent with respect to the Expansion
Space until the Expansion Space Commencement Date. Upon request from Landlord,
Tenant shall enter into a written amendment of the Lease prepared by Landlord
and memorializing the expansion of the Premises to include the Expansion Space
and the adjustment of the other economic terms of the Lease.

     (E) In consideration of Landlord's granting the Expansion Option and with
the understanding that Landlord would not have otherwise agreed to the Expansion
Option, Tenant shall pay to Landlord upon execution of this Lease and on the
first day of each succeeding calendar month the sum of [...***...] (the "Carry
Costs") until such time as (i) Tenant notifies 


*CONFIDENTIAL TREATMENT REQUESTED


                                      50.


<PAGE>   57
Landlord that it has relinquished the Expansion Option, (ii) the Expansion
Option expires in accordance with the terms of this Paragraph 52 or, (iii) if
the Tenant delivers an Expansion Notice, until ten (10) months prior to the
Requested Delivery Date (said amounts to be prorated during any partial calendar
months hereunder). Notwithstanding the foregoing, Tenant may elect, by
delivering written notice of such election to Landlord upon execution of this
Lease, to pay on the Commencement Date all Carry Costs due for the period of
time from the date of this Lease through the Commencement Date, together with
interest thereon at the rate of [...***...] per annum. All Carry Costs due from
and after the Commencement Date shall be paid to Landlord on a monthly basis as
set forth above. Any delays in delivery of the Expansion Space beyond the
Requested Delivery Date due to Tenant Delays or Force Majeure Events, as such
terms are defined in Exhibit B hereto, shall result in Tenant's continued
payment of Carry Costs for the time attributable to the such delay.

     (F) Promptly after the exercise of the Expansion Option by Tenant, Landlord
and Tenant shall enter into a building construction agreement and a premises
construction agreement (collectively, the "Expansion Construction Agreements")
in form and content substantially similar to the Building Construction Agreement
and Premises Construction Agreement attached hereto as Exhibit A and Exhibit B,
respectively, which Expansion Construction Agreements shall set forth the rights
and obligations of the parties with respect to the construction of the Expansion
Building and the Premises. Without limiting the foregoing, the building
construction agreement for the Expansion Space shall include Conditions
substantially similar to those set forth on Exhibit H with respect to the
Original Premises and performance periods for the satisfaction of such
Conditions of equivalent duration to the performance periods specified on said
Exhibit H (as measured by the time periods from the date of this Lease to the
respective Initial Window Dates). Landlord shall provide Tenant with a Tenant's
Allowance equal to the Expansion Space TI Dollars, as defined below, multiplied
by the Expansion this Paragraph, the Space square footage, as finally
determined. As used in "Expansion Space TI Dollars" shall mean an amount equal
to [...***...] increased at an annualized rate of [...***...] from the date of
this Lease until the date the Expansion Notice is properly given.

53.     MEMORANDUM OF LEASE.

        Promptly after full execution of this Lease, Landlord and Tenant shall
execute and cause to be recorded a Memorandum of Lease in the form attached
hereto as Exhibit J.

                            (signatures on next page)


*CONFIDENTIAL TREATMENT REQUESTED


                                      51.


<PAGE>   58
        Landlord and Tenant have executed and delivered this Lease as of the
Lease Date specified in the Basic Lease Information.

                         LANDLORD:

                         HMS GATEWAY OFFICE, L.P.,
                         A Delaware limited liability company


                         By:    HINES GATEWAY OFFICE, L.P.,
                                General Partner


                         By:    HINES INTERESTS LIMITED PARTNERSHIP,
                                General Partner


                         By:    HINES HOLDING, INC.
                                General Partner

                         By:    /s/ James Bule
                            -------------------------------  
                         Name:     James Bule
                            -------------------------------  
                         Its:   EVP
                             ------------------------------ 

                         TENANT:

                         COULTER PHARMACEUTICAL, INC.,
                         A Delaware corporation

                         By:    /s/ William G. Harris
                            -------------------------------  
                         Name:     William G. Harris
                            -------------------------------  
                         Its:   VP & CFO
                             ------------------------------ 


                                      52.


<PAGE>   59
                                    EXHIBIT A

                      BASE BUILDING CONSTRUCTION AGREEMENT

        This exhibit, entitled "Base Building Construction Agreement", is and
shall constitute Exhibit A to the Lease Agreement, dated as of the Lease Date,
by and between Landlord and Tenant. The terms and conditions of this Exhibit A
are hereby incorporated into and are made a part of the Lease.

        Subject to the terms and conditions set forth herein and in the Lease,
Landlord shall cause construction of the Building in accordance with the
procedures set forth below:

     (A)   DEFINITIONS.

          (1) "BASE BUILDING IMPROVEMENTS" shall mean a two (2) story building,
containing approximately [...***...] square feet, all exterior surfaces,
utilities, landscaping and paved parking, all in substantial compliance with
those items listed on the Preliminary Specifications as "Base Building" and
located substantially in accordance with the Site Plan.

          (2) "BASE BUILDING PLANS AND SPECIFICATIONS" is defined in Section B.
1 below.

          (3) "BUILDING WORK COST" is defined in Section B.3 below.

          (4) "CONSTRUCTION WARRANTIES" is defined in Section D.2 below.

          (5) "LANDLORD'S ARCHITECT" shall mean DES Architects/Engineers or any
replacement architect selected by Landlord in Landlord's reasonable discretion.

          (6) "LANDLORD'S CONTRACTOR" shall mean a general contractor and any
replacement general contractors selected by Landlord in Landlord's reasonable
discretion.

          (7) "PRELIMINARY SPECIFICATIONS" shall mean those preliminary
specifications for construction of the Base Building Improvements categorized as
"Base Building" and more particularly described on the attached Schedule A-1.

          (8) "SITE PLAN" shall mean the site plan set forth on the attached
Schedule A-2 establishing the approximate location of the Building. All details
relating to the Project contained on the Site Plan, including without
limitation, location of the Building, parking areas, ingress, egress, direction
of driveways, and entrances are from time to time subject to change in
Landlord's discretion, upon written consent from Tenant, which consent shall not
be unreasonably withheld, conditioned or delayed and provided further that if
Tenant fails to respond within five (5) business days following Landlord's
request for consent, Tenant shall be conclusively deemed to have given its
approval to any such change. Notwithstanding the foregoing, Landlord may,
without the written consent of Tenant, change any details relating to the
Project as may be required by any governmental agency or as necessary to comply
with any 


*CONFIDENTIAL TREATMENT REQUESTED


                                      53.


<PAGE>   60
governmental requirements or to address structural or unanticipated field
conditions or which, in the reasonable discretion of Landlord, will not have a
material effect on Tenant's use of the Premises or a material effect on the
aesthetic appearance or impression relating to the area covered by the Site
Plan.

          (9) "TENANT'S COSTS" is defined in Section B.6 below.

          (10) "TENANT REQUESTED BASE BUILDING IMPROVEMENTS" shall mean those
improvements requested by Tenant in accordance with this Exhibit A that are to
be incorporated into the Base Building Plans and Specifications. Capitalized
terms not otherwise defined in this Exhibit A shall have the meanings ascribed
to them in the Lease.

     (B)   SCHEDULE.

          (1) PLANS AND SPECIFICATIONS. At Landlord's sole cost and expense,
Landlord's Architect has prepared schematic plans and specifications (the "Base
Building Plans and Specifications") for construction of the Base Building
Improvements substantially in accordance with the Preliminary Specifications,
which plans are commonly referred to as the "September 5, 1997 Schematic
Drawings," as such drawings were modified by the City Council of the City of
South San Francisco on October 15, 1997. Tenant has reviewed and approved the
Base Building Plans and Specifications. Notwithstanding the foregoing, the Base
Building Plans and Specifications are, from time to time, subject to change in
Landlord's discretion, upon written consent from Tenant, which consent shall not
be unreasonably withheld, conditioned or delayed and provided further that if
Tenant fails to respond within [...***...] business days following Landlord's
request for consent, Tenant shall be conclusively deemed to have given its
consent to any such change. Landlord may without the written consent of the
Tenant change the Base Building Plans and Specifications as may be required by
any governmental agency or as necessary to comply with any governmental
requirements or to address structural or unanticipated field conditions or
which, in the reasonable discretion of Landlord, will not have a material effect
on Tenant's use of the Premises or a material effect on the aesthetic appearance
or impression relating to the Base Building Improvements.

          (2) TENANT REQUESTED BASE BUILDING IMPROVEMENTS. On or before the date
that is [...***...] weeks after the date of this Lease, Tenant shall deliver to
Landlord's Architect detailed specifications for any Tenant Requested Base
Building Improvements. All Tenant Requested Base Building Improvements shall be
subject to review and approval by Landlord, which approval may be given or
withheld in Landlord's reasonable discretion, to ensure, among other things,
that the Tenant Requested Base Building Improvements are compatible with all
other construction and all electrical, mechanical, life safety, and other
systems within the Building. If Landlord disapproves the Tenant Requested Base
Building Improvements, then within five (5) business days thereafter, Landlord
shall meet with the Tenant's Architect (as defined in Exhibit B) and Tenant to
discuss, or shall submit to Tenant's Architect and Tenant in writing, the
reasons for Landlord's disapproval. Within five (5) business days following such


*CONFIDENTIAL TREATMENT REQUESTED


                                      54.


<PAGE>   61
meeting 6i' submission, Tenant shall cause Tenant's Architect to revise the same
and to submit new Tenant Requested Base Building Improvements to Landlord. The
procedure set forth in this paragraph will be repeated as set forth above until
Landlord has approved the Tenant Requested Base Building Improvements.

          (3) ESTIMATE OF BUILDING WORK COSTS. Promptly after approval of the
Tenant Requested Base Building Improvements, Landlord shall furnish Tenant with
an estimate of the cost of the Tenant Requested Base Building Improvements (the
"Building Work Cost").

          (4) TENANT'S REVIEW OF BUILDING WORK COSTS. The Building Work Cost
shall be subject to Tenant's approval, which approval shall not be unreasonably
withheld, conditioned or delayed and provided further that if Tenant fails to
respond within five (5) business days following Landlord's request for consent,
Tenant shall be conclusively deemed to have given its approval to the Building
Work Costs. If Tenant timely disapproves the Building Work Cost, then within
five (5) business days thereafter, Tenant shall meet with Landlord, Landlord's
Contractor, Landlord's Architect and Tenant's Architect to discuss value
engineering changes to the Tenant Requested Base Building Improvements. Within
five (5) business days following such meeting, Tenant shall cause Tenant's
Architect to revise the Tenant Requested Base Building Improvements and to
submit revised Tenant Requested Base Building Improvements for approval by
Landlord in accordance with the procedure set forth above and for a new Building
Work Cost to be prepared by Landlord. The procedure set forth in this paragraph
will be repeated until Tenant has approved the Building Work Cost.

          (5) REVISION OF PLANS & SPECIFICATIONS. Following Landlord's approval
of the Tenant Requested Base Building Improvements and Tenant's approval of the
Building Work Cost, Landlord shall cause Landlord's Architect to revise the Base
Building Plans and Specifications to incorporate the Tenant Requested Base
Building Improvements.

          (6) TENANT'S RESPONSIBILITY FOR COST OF TENANT REQUESTED BASE BUILDING
IMPROVEMENTS. All costs associated with incorporating the Tenant Requested Base
Building Improvements into the Base Building Plans and Specifications and all
costs of constructing the Tenant Requested Base Building Improvements (the
"Tenant's Costs") shall be the responsibility of Tenant and shall not be
credited against Tenant's Allowance, as defined in Exhibit B. Tenant shall make
progress payments to Landlord from time to time as the Tenant Requested Base
Building Improvements are constructed. Tenant shall pay the portion of such
progress payments attributable to Tenant's Costs to Landlord within ten (10)
days of delivery of statements from Landlord to Tenant therefor. Upon receipt of
such payments, Landlord shall make all progress payments directly to Landlord's
Contractor or subcontractors, as appropriate. Landlord shall be entitled to
suspend or terminate construction of the Base Building Improvements and to
declare Tenant in default in accordance with the terms of the Lease, if payment
by Tenant to Landlord of Tenant's Costs has not been received as required
hereunder.

     (C)   CONSTRUCTION.

        The Base Building Improvements shall be constructed, at Landlord's sole
cost and expense, by Landlord's Contractor in accordance with the Base Building
Plans and Specifications, as the same may be amended or modified from time to
time by Landlord and, if 


                                      55.


<PAGE>   62
required, as approved by Tenant in accordance with this Exhibit A. All changes
to the Base Building Plans and Specifications requiring Tenant's approval must
be evidenced by a written change order executed by Landlord and by Tenant or
each of their agents, describing the change required in the Base Building
Improvements and, the cost of such changes shall be paid in accordance with the
terms of this Exhibit A.

     (D)   GENERAL.

          (1) RIGHT OF TERMINATION. Landlord and Tenant acknowledge that
construction of the Base Building Improvements and all matters relating thereto
are subject to Landlord obtaining all necessary governmental and private
approvals to commence construction of the Base Building Improvements. Landlord
shall use commercially reasonable efforts to obtain such approvals; however, if
Landlord is unable to obtain such approvals by [...***...],.either party shall
have the right to terminate' this Lease by delivering written notice of
termination to the other party on or before [...***...]. If written notice of
termination is given in a timely manner, the Lease shall immediately terminate,
except for any obligations which by their terms survive the termination or
earlier expiration of the Lease. Upon termination of the Lease in accordance
with this provision, Tenant shall receive a return of all Carry Costs, if any,
paid to Landlord pursuant to Paragraph 52(e) of the Lease. If no such notice of
termination is given, the Lease shall remain in full force and effect.
Notwithstanding anything herein to the contrary, Landlord shall not be liable to
Tenant for any loss or damage resulting from any delay in constructing or
developing the Base Building Improvements, nor shall such failure affect the
obligations of Tenant under the Lease, except as otherwise set forth in the
Lease.

          (2) CONSTRUCTION WARRANTIES. Landlord shall obtain from Landlord's
Contractor, and shall request Landlord's Contractor to obtain from all
subcontractors and material suppliers, warranties (collectively, "Construction
Warranties") for all components of the Base Building Improvements for which
warranties are customarily provided in the construction industry and Landlord
shall enforce the Construction Warranties as reasonably requested by Tenant.

          (3) LANDLORD'S COVENANTS. Subject to the terms and conditions of the
Lease, Landlord covenants that (a) the Base Building Improvements shall be
constructed in compliance with all applicable building code requirements in
effect and being actively enforced by the City of South San Francisco on the
date the applicable building permits for construction of the Base Building
Improvements were issued to Landlord's Contractor and substantially in
accordance with the Base Building Plans and Specifications and (b) that the Base
Building Improvements shall be free from material latent defects in design,
materials and workmanship; provided however, Landlord shall have no liability
under this paragraph unless failure to comply with the terms hereof materially
adversely affect Tenant's use of the Premises. Any claims by Tenant under clause
(a) above, shall be made in writing not later than one (1) year after
commencement of the Term and any claims by Tenant under clause (b) above, shall
be made in writing not later than the earlier of [...***...] years after
commencement of the Term or termination of the Lease. In the event Tenant fails
to deliver a written claim to Landlord on or before such dates, then 


*CONFIDENTIAL TREATMENT REQUESTED


                                      56.


<PAGE>   63
Landlord shall be conclusively deemed to have satisfied its obligations under
this paragraph. The covenants contained in this paragraph are subject to
Paragraph 39 of the Lease and are made specifically and exclusively for the
benefit of the original Tenant.

INITIALS:

TENANT:

LANDLORD:


                                      57.


<PAGE>   64
                      COULTER PHARMACEUTICAL - SCHEDULE A1
                           PRELIMINARY SPECIFICATIONS
                               COST RESPONSIBILITY 


<TABLE>
<CAPTION>
                                                                                                Base
                               Description                                                    Building           Tenant
                               -----------                                                    --------           ------
                                                                              
SITEWORK

<S>                                                                                          <C>               <C>
- All necessary fees and permits for Base Building Works                                     [...***...]       [...***...]

- All grading of the site to predetermined grades per DES Architects plans                   [...***...]       [...***...]

- Installation of all necessary underground utilities, storm drain,                          [...***...]       [...***...]
  sewer, catch basins, drain inlets, common trench, water, electricity,
  cable televisions and gas meter per DES Architects documents 

- Installation of all offsite and onsite curbs, gutters and sidewalks                        [...***...]       [...***...]
  as shown on Des Architect construction documents  

- Installation of all irrigation and landscaping per DES Architect's plans                   [...***...]       [...***...]

- All area drains in landscaping areas, which shall be connected to the storm                [...***...]       [...***...]
  drain system if required by DES Architect

- Installation of separate water and electrical meters for all common area landscaping       [...***...]       [...***...]

- Installation of code required informational and directional signage                        [...***...]       [...***...]

- Illuminated and non-illuminated interior signage by tenant                                 [...***...]       [...***...]

- Illuminated monument signage and on building identification                                [...***...]       [...***...]
  signage as reviewed by Tenant 

- Striping of all parking areas per DES Architects documents                                 [...***...]       [...***...]

- Installation of all trash screens as required by Planning Department of                    [...***...]       [...***...]
  the City of South San Francisco

- Installation of all exterior lighting with a minimum coverage in both                      [...***...]       [...***...]
  parking areas and walkways of not less than one foot candle 


STRUCTURE

- All necessary fees and permits for Base Building work                                      [...***...]       [...***...]

- All work necessary per code to make the Base Building handicap accessible                  [...***...]       [...***...]

- Minimum 5" slab on grade in conformance with specifications and                            [...***...]       [...***...]
  recommendations of Base Building geotechnical and engineering consultants.
  Finish shall be smooth.

- Sand fill and moisture barrier under slab on grade as recommended                          [...***...]       [...***...]
  by DES Architects 

- Exterior concrete walls shall be sandblasted and sealed                                    [...***...]       [...***...]

- All structural steel shall be erected per DES Architect's specifications                   [...***...]       [...***...]

- All structural steel shall not be fireproofed unless required by local codes               [...***...]       [...***...]

- Second floor decking shall be galvanized metal with a lightweight                          [...***...]       [...***...]
  concrete topping slab.  Finish shall be smooth 

- All exterior vision glass shall be 1/4" thick with reflective coating                      [...***...]       [...***...]

- Roof membrane shall be 4-ply built-up system with a mineral fiber                          [...***...]       [...***...]
  cap sheet.  Walk pads shall be installed to Base Building roof
  mounted equipment, including fan units 

- All roof penetrations per Base Building drawings and specifications                        [...***...]       [...***...]

- All roof and floor penetrations per tenant drawings and specifications                     [...***...]       [...***...]

- All required condensate lines to be installed and terminated at the                        [...***...]       [...***...]
  nearest roof drain for Base Building equipment 
</TABLE>


*CONFIDENTIAL TREATMENT REQUESTED


                                       1.


<PAGE>   65
                      COULTER PHARMACEUTICAL - SCHEDULE A1
                           PRELIMINARY SPECIFICATIONS
                               COST RESPONSIBILITY 


<TABLE>
<CAPTION>
                                                                                                Base
                               Description                                                    Building           Tenant
                               -----------                                                    --------           ------
                                                                              
SITEWORK

<S>                                                                                          <C>               <C>
- Roof drains per plan with drain lines tying into the storm drain system                    [...***...]       [...***...]
  Scuppers for overflow to be provided if required by code 

- Convenience outlets, as required by code, on the roof                                      [...***...]       [...***...]

- Floor systems shall be designed to a minimum of 45 lbs. Per square foot                    [...***...]       [...***...]
  for office space and a minimum of 100 lbs. Per square foot on ground
  floor for lab space 

- Roof insulation to meet minimum energy code                                                [...***...]       [...***...]

- Roof live load to accommodate dead load and necessary reinforcement for                    [...***...]
  additional lab related mechanical equipment 

- Required roof and floor penetrations, including blockouts, as shown on                     [...***...]       [...***...]
  base building for mechanical, electrical and plumbing trades 

- Required roof and floor penetrations, including blockouts, as shown on                     [...***...]       [...***...]
  tenant improvement drawings for tenant required mechanical, electrical
  and plumbing work 

- Top of slab on grade to top of second floor slab shall be 15'-0"                           [...***...]       [...***...]
  Top of second floor slab to top of roof trusses shall be 13'-0" 

- All exterior doors, except entrance doors, shall be hollow core metal                      [...***...]       [...***...]
  with metal jambs as shown in schematic documents 

- One 12'-0" x 12'-0" steel rollup door shall be installed per Tenant                        [...***...]       [...***...]
  specifications for delivery area 

- Front entry doors shall be a pair of 3'-0" x 8'-0" fully supported,                        [...***...]       [...***...]
  balanced aluminum and glass doors with hardware reviewed by Tenant 

- All interior stairs as required by code, but not less than two per                         [...***...]       [...***...]
  building.  All stairs shall be checker plate.  If metal pan stairs
  with concrete fill are requested by tenant, Coulter Pharmaceutical
  pays the difference 
 
- Stair carpeting, if required, to be provided tenant                                        [...***...]       [...***...]

- All interior stair handrails shall be primed and painted.  Proper                          [...***...]       [...***...]
  backing shall be installed 

- All stairwells shall be sheetrocked, taped and ready for paint                             [...***...]       [...***...]

- All stairwells shall include code required lighting                                        [...***...]       [...***...]

- All required base building life safety signage as required by code                         [...***...]       [...***...]

- All necessary equipment platforms on roof with a curb height of                            [...***...]       [...***...]
  not less than 10". All equipment platforms shall have a sheetmetal cap
  and minimum 3" apron around the perimeter 

- One hydraulic passenger elevator, including all necessary wiring                           [...***...]       [...***...]
  and equipment, with a capacity of not less than 3,000 lbs. and
  minimum speed of 100' per minute 

- A complete elevator cab that is the manufacturer's standard                                [...***...]       [...***...]

- Base Building to accommodate a 9'-0" finished ceiling height on both floors                [...***...]       [...***...]

- All exterior concrete walls shall be finished on the interior with lightweight             [...***...]       [...***...]
  metal studs, insulation and sheetrock, taped with a smooth finish 

- Master keyed exterior locks                                                                [...***...]       [...***...]

- Individual keying per tenant specifications                                                [...***...]       [...***...]

- A complete fire sprinkler system, sized to meet code for a complete                        [...***...]       [...***...]
  open plan floorplate.  This system shall be complete and operational except
  for required drops to the suspended ceiling in tenant finished areas
  The system shall include, but is not limited to, valves, dry stand pipes,
  monitoring stations, ennciators, horns and storage tanks, if required by code

- Roof access ladder and hatch in one stairwell                                              [...***...]       [...***...]
</TABLE>


*CONFIDENTIAL TREATMENT REQUESTED


                                       2.


<PAGE>   66
                      COULTER PHARMACEUTICAL - SCHEDULE A1
                           PRELIMINARY SPECIFICATIONS
                               COST RESPONSIBILITY 


<TABLE>
<CAPTION>
                                                                                                Base
                               Description                                                    Building           Tenant
                               -----------                                                    --------           ------
Sitework

<S>                                                                                          <C>               <C>
UTILITIES AND BACKBONE SYSTEMS                                                               [...***...]       [...***...]

- 2,000 amp. 277/480 volt, 3 phase electrical service switchgear and meter                   [...***...]       [...***...]
  and switch center room 

- Separate electrical meter, panel and time clock for Parking lot lighting                   [...***...]       [...***...]
  and irrigation 

- Telephone trunk lines to the interior telephone room sufficient in size                    [...***...]       [...***...]
  to accommodate both the first and option buildings 

- Two PVC conduits, minimum of 4" between the first and option buildings                     [...***...]       [...***...]
  for telephone and data 

- Required water service for sprinkler system                                                [...***...]       [...***...]

- A minimum of 2" domestic water service to building.  There shall be a                      [...***...]       [...***...]
  separate meter for this water line and it shall terminate inside the
  building below the second floor 

- A minimum 2" natural gas service building.  There shall be a separate                      [...***...]       [...***...]
  meter for this service and it shall terminate inside the building
  below the second floor 

- As required, a 6" cast iron, sanitary sewer gut line the entire length                     [...***...]       [...***...]
  of the building.  This gut line shall have, at a minimum, one cleanout
  at the end of its run, one in the restroom core and one cleanout at the
  entrance to the building.  Exact location of this gut line shall be
  determined by tenant 

- All necessary electrical and fire sprinkler rooms, sized to accommodate                    [...***...]       [...***...]
  Tenant requirements, shall be completed with light weight metal studs,
  metal doors and jambs, required ventilation through the roof membrane,
  lighting, convenience outlets and sheetrock, taped and textured 


MEP

- All required electrical to base building equipment                                         [...***...]       [...***...]

- All backboards as required by Tenant                                                       [...***...]       [...***...]

- All required electrical outlets and lighting to complete base                              [...***...]       [...***...]
  building requirements 

- Smoke detectors as required by code for Base Building                                      [...***...]       [...***...]

- All required roof walk pads, conduit supports, and penetrations for Base                   [...***...]       [...***...]
  Building equipment 

- All sheetmetal necessary to provide moisture protection and flashing details               [...***...]       [...***...]
  for Base Building equipment 

- All necessary seismic restraints on Base Building equipment                                [...***...]       [...***...]

- A centrally located, gas hot water heater large enough to accommodate all                  [...***...]       [...***...]
  of the tenant requirements including hot water to all labs.  Coulter
  pay difference in cost vs. standard system 

- A mechanical chiller system, sized to accommodate 50,000 square feet                       [...***...]       [...***...]
  of office space 

- All ductwork and penetrations necessary to provide both supply and return                  [...***...]       [...***...]
  air to each floor, elevator cores and lobby restrooms shall be provided 
  All necessary fire and smoke dampers shall be included for Base Building
  work. Restrooms, elevator cores, lobby and stairwells shall be complete 

- All ductwork and roof mounted fans necessary to provide proper                             [...***...]       [...***...]
  ventilation in the restrooms 

- Screening of Base Building roof mounted equipment                                          [...***...]       [...***...]

- Screening of tenant installed rooftop equipment                                            [...***...]       [...***...]

- Exhaust ducts, through the roof, for lab ventilating as specified by Tenant                [...***...]       [...***...]
</TABLE>


*CONFIDENTIAL TREATMENT REQUESTED


                                       3.


<PAGE>   67
<TABLE>
<CAPTION>
                                                                                                Base
                               Description                                                    Building           Tenant
                               -----------                                                    --------           ------
SITEWORK
<S>                                                                                          <C>               <C>
- Hose bib is near delivery and trash areas                                                  [...***...]       [...***...]


LOBBY AREA

- Landlord's architect design fees associated with the lobby area                            [...***...]       [...***...]

- Two story height with skylight, visibility to stairwell and a                              [...***...]       [...***...]
  catwalk and overlook at the second floor level 

- Area of Lobby to be 30' x 30'                                                              [...***...]       [...***...]

- All walls sheetrocked, taped with a smooth finish.  If Tenant so                           [...***...]       [...***...]
  desires, all walls will be prepared and ready to accept wallcovering 

- Electrical outlets, telephone outlets and data outlets necessary                           [...***...]       [...***...]
  to accommodate the Tenant's proposed lobby layout 

- Ceramic tile entry, 8'-0" wide, from the front doors to the reception                      [...***...]       [...***...]
  counter.  All other areas to be carpet, a 36 oz. loop mix minimum, and 
  if desired by Tenant, with a border 

- 6" or 2" rubber base in all areas                                                          [...***...]       [...***...]

- Entry doors to be a pair of aluminum glass with hardware reviewed by Tenant                [...***...]       [...***...]

- All doors off of lobby to be wood grain, 3'-0" x 8'-0" minimum in                          [...***...]       [...***...]
  height.  Hardware to be selected by tenant                                                   

- All HVAC to be complete                                                                    [...***...]       [...***...]

- All Base Building areas to be handicap accessible per code                                 [...***...]       [...***...]

- All finishes to be reviewed by Tenant                                                      [...***...]       [...***...]

- Ceiling to be sheetrock, taped and textured                                                [...***...]       [...***...]

- Lighting to include, but not be limited to, down lights, recessed wall washers,            [...***...]       [...***...]
  recessed parabolic or halogen    

- Wallcovering on all walls if so desired by Tenant                                          [...***...]       [...***...]

- Fully painted to Tenant specifications                                                     [...***...]       [...***...]


ELEVATOR LOBBIES

- Sheetrock walls and ceiling, taped with a smooth finish                                    [...***...]       [...***...]

- Ceiling to have a multiple coffer with lighting behind                                     [...***...]       [...***...]

- Electrical outlets to support work required in the area                                    [...***...]       [...***...]

- Stainless steel jambs and head around elevator opening ground floor                        [...***...]       [...***...]

- Painted hollow metal jambs and head on 2nd floor                                           [...***...]       [...***...]

- Nickel/silver threshold and elevator entrance                                              [...***...]       [...***...]

- Grout under elevator thresholds                                                            [...***...]       [...***...]

- Carpet, 36 oz. loop minimum, and if desired by Tenant, with a border                       [...***...]       [...***...]

- 6" and 2" rubber base at all areas                                                         [...***...]       [...***...]

- Magnetic hold opens on all lobby doors if required by code                                 [...***...]       [...***...]

- Lobby door to be wood grain, full height, with hardware reviewed by Tenant                 [...***...]       [...***...]

- Lighting to include recessed down lights, recessed lights or wall washers                  [...***...]       [...***...]

- Fully painted to Tenant specifications                                                     [...***...]       [...***...]

- All HVAC to be complete                                                                    [...***...]       [...***...]

- All elevator lobby areas to have a one hour rating if required by code                     [...***...]       [...***...]


RESTROOMS


- Sheetrock walls taped with a smooth finish A cofer shall be installed over the             [...***...]       [...***...]
</TABLE>


*CONFIDENTIAL TREATMENT REQUESTED


                                       4.


<PAGE>   68
<TABLE>
<CAPTION>
                                                                                                Base
                               Description                                                    Building           Tenant
                               -----------                                                    --------           ------
SITEWORK
<S>                                                                                          <C>               <C>
  vanity area 

- Ceiling to be drywall                                                                      [...***...]       [...***...]

- Ceramic tile floors and wainscot on wet wall                                               [...***...]       [...***...]

- All floors sloped to a floor drain                                                         [...***...]       [...***...]

- Light cove with egg crate louver over stalls and urinals                                   [...***...]       [...***...]

- Provide janitor closets on each floor adjacent to restrooms                                [...***...]       [...***...]

- Provide sinks in janitor closets                                                           [...***...]       [...***...]

- Recessed lighting at entry, sinks and outside stalls                                       [...***...]       [...***...]

- All partitions to be meal and hung from wall                                               [...***...]       [...***...]

- All toilets and urinals to be hung from wall                                               [...***...]       [...***...]

- Plastic laminate counter tops over moisture resistant plywood with                         [...***...]       [...***...]
  5' lipped apron and 6" splash 

- Full length B.B. mirror with polished stainless steel frame                                [...***...]       [...***...]

- Provide insulation for hot and cold water pipes                                            [...***...]       [...***...]

- Minimum toilet accessories to include, but not limited to, sinks,                          [...***...]       [...***...]
  stainless faucets, toilets, urinals, recessed paper towel dispensers
  with integral waste, counter mounted soap dispensers, sanitary napkin
  dispenser, seat cover dispenser, toilet tissue dispenser, handicap grab
  bars and partition mounted coat hooks 

- Paint above wainscot as directed by Tenant                                                 [...***...]       [...***...]
</TABLE>


*CONFIDENTIAL TREATMENT REQUESTED


                                       5.


<PAGE>   69

                                  SCHEDULE A-1

                                    SITE PLAN

                             [GRAPHIC - MAP OF SITE]


                                       1.


<PAGE>   70
                                    EXHIBIT B

PREMISES CONSTRUCTION AGREEMENT

        This exhibit, entitled "Premises Construction Agreement", is and shall
constitute Exhibit B to the Lease Agreement, dated as of the Lease Date, by and
between Landlord and Tenant. The terms and conditions of this Exhibit B are
hereby incorporated into and are made a part of the Lease.

        Subject to the terms and conditions set forth herein and in the Lease,
Landlord shall allow the construction or installation of the improvements in the
interior of the Premises in accordance with the procedures set forth below:

     (A)       DEFINITIONS.

          (1) "APPROVED PLANS" is defined in Section B.6 below.

          (2) "TENANT'S ARCHITECT" shall mean CAS Architects, or such other
licensed architect designated by Tenant and subject to Landlord's prior
approval, which approval shall be given or withheld in Landlord's reasonable
discretion.

          (3) "TENANT'S CONTRACTOR" shall mean Rudolph and Sletten, Inc., or
such other contractor designated by Tenant and subject to Landlord's prior
approval, which approval shall be given or withheld in Landlord's reasonable
discretion.

          (4) "ESTIMATED WORK COST" is defined in Section B.3 below.

          (5) "EXCESS TENANT IMPROVEMENTS" is defined in Section B.7 below.

          (6) "FINAL COST QUOTATION" is defined in Section B.7 below and shall
include all costs associated with the Tenant Improvements, including without
limitation, costs of all tenant improvement work; architectural and engineering
fees; governmental agency fees for permits, licenses and inspections;
construction fees, including, without limitation, general contractors' overhead
and supervision fees; Landlord's administration fee of [...***...]; and such
other costs as may be reasonably incurred by Landlord in connection with such
construction.

          (7) "LANDLORD'S CONTRACTOR" is defined in Section A.6 of Exhibit A.

          (8) "PRELIMINARY PLANS" is defined in Section B.  1 below.

          (9) "TENANT'S ALLOWANCE" shall mean an amount equal to [...***...],
which amount shall, except as otherwise provided in this Exhibit B, be paid by
Landlord toward the cost of completion of the Tenant Improvements and related
design, engineering, governmental, overhead, supervision and administration fees
and costs (collectively, the "Tenant Improvement Cost"). Notwithstanding the
foregoing, no portion of the Tenant's Allowance shall be paid by 


*CONFIDENTIAL TREATMENT REQUESTED


                                       1.


<PAGE>   71
Landlord toward the cost of the Tenant Requested Base Building Improvements, or
Tenant Improvements that constitute furniture, equipment or trade fixtures or
result in changes to the Base Building Improvements. If the Tenant Improvement
Cost exceeds the Tenant's Allowance, the difference shall be paid by Tenant in
accordance with this Exhibit B.

          (10) "TENANT IMPROVEMENTS" shall mean all improvements made to the
Premises pursuant to the Approved Plans.

Capitalized terms not otherwise defined in this Exhibit B shall have the
meanings ascribed to them in the Lease.

     (B)       SCHEDULE.

          (1) Tenant shall cause Tenant's Architect to furnish to Landlord on or
before [...***...], preliminary space plans and specifications (the "Preliminary
Plans"). Tenant shall be responsible for all costs associated with the
Preliminary Plans (collectively, the "Preliminary Design Costs"), including any
revisions required by Section B.2 hereunder; provided, however, Tenant shall be
reimbursed by Landlord out of the Tenant's Allowance for the Preliminary Design
Costs reasonably incurred upon delivery to Landlord of invoices, receipts and
other documents reasonably required to substantiate such costs.

          (2) The Preliminary Plans shall be subject to Landlord's approval,
which approval shall not be unreasonably withheld, conditioned or delayed. If
Landlord disapproves the Preliminary Plans, then within five (5) business days
thereafter, Landlord shall meet with the Tenant's Architect and Tenant to
discuss, or shall submit to the Tenant's Architect and Tenant in writing, the
reasons for Landlord's disapproval. Within five (5) business days following such
meeting or submission, Tenant shall cause the Tenant's Architect to revise the
same and to submit new Preliminary Plans to Landlord. The same procedure set
forth in this paragraph will be repeated as set forth above until Landlord has
approved the Preliminary Plans.

          (3) Promptly after approval of the Preliminary Plans, Tenant shall
cause Tenant's Contractor to furnish Landlord with an estimate of the cost of
the Tenant Improvements as shown on the Preliminary Plans and Landlord shall in
turn provide Tenant with an estimate of the cost of the Tenant Improvements,
including, without limitation, estimates of the following costs: architectural
and engineering fees, governmental agency fees for permits, licenses and
inspections, overhead and supervision fees, and Landlord's administrative fees
(the "Estimated Work Cost"). The Estimated Work Cost shall separately itemize
the cost of changes to the Base Building Improvements for those Tenant
Improvements that will necessitate changes in the Base Building Improvements.

          (4) The Estimated Work Cost shall be subject to Tenant's approval,
which approval shall not be unreasonably withheld, conditioned or delayed and
provided further that if Tenant fails to respond within five 


*CONFIDENTIAL TREATMENT REQUESTED


                                       2.


<PAGE>   72
(5) business days following Landlord's delivery of the Estimated Work Cost,
Tenant shall be conclusively deemed to have given its approval of the Estimated
Work Cost. If Tenant timely disapproves the Estimated Work Cost, then within
five (5) business days thereafter, Tenant shall meet with Landlord, Tenant's
Contractor, Landlord's Contractor and Tenant's Architect to discuss value
engineering changes to the Preliminary Plans. Within five (5) business days
following such meeting, Tenant shall cause Tenant's Architect to revise the
Preliminary Plans and to submit new Preliminary Plans for approval by Landlord
in accordance with the procedure set forth above and for a new Estimated Work
Cost to be prepared by Landlord. The procedure set forth in this paragraph will
be repeated until Tenant has approved the Estimated Work Cost.

          (5) Following Landlord's approval of the Preliminary Plans and
Tenant's approval of the Estimated Work Cost, Tenant shall cause Tenant's
Architect to prepare detailed construction drawings and specifications (the
"Working Drawings") for the Tenant Improvements based strictly upon the
Preliminary Plans, except as otherwise agreed in writing by Landlord and Tenant.
The Working Drawings shall be completed within [...***...] business days after
approval of the Preliminary Plans and Estimated Work Cost, but in no event later
than [...***...].

          (6) The Working Drawings shall be subject to Landlord's approval,
which approval shall not be unreasonably withheld, conditioned or delayed. If
Landlord disapproves the Working Drawings, then within five (5) business days
thereafter, Landlord shall meet with Tenant's Architect and Tenant to discuss,
or shall submit to the Tenant's Architect and Tenant in writing, the reasons for
Landlord's disapproval. Within five (5) business days following such meeting or
submission, Tenant shall cause Tenant's Architect to revise the same and to
submit new Working Drawings to Landlord, and the same procedure will be repeated
as set forth above until Landlord has approved the Working Drawings (the
"Approved Plans"). The reasonable costs of preparing the Working Drawings,
together with any revisions thereto, may be paid by Landlord to Tenant from
Tenant's Allowance. Upon approval of the Working Drawings, Landlord shall
deliver to Tenant a list of Tenant Improvements to be removed by Tenant, at
Tenant's cost and expense in accordance with Paragraph 11 of the Lease, upon
expiration of the Term or earlier termination of the Lease. Notwithstanding the
foregoing, during the preparation of the Working Drawings, Landlord shall, upon
Tenant's request, advise Tenant of items that will be required to be removed
pursuant to the previous sentence.

          (7) Within ten (10) business days after Landlord's approval of the
Approved Plans, Tenant shall cause Tenant's Contractor to furnish to Landlord a
cost estimate for the Tenant Improvements based upon the Approved Plans and
Landlord shall in turn provide Tenant with a final cost quotation for the Tenant
Improvements (the "Final Cost Quotation"). If the Final Cost Quotation is
greater than the Tenant's Allowance, Tenant shall be responsible for the
difference between the Tenant's Allowance and the Final Cost Quotation (the
"Excess Tenant Improvements Cost").

          (8) Landlord and Tenant shall make progress payments on a pro rata
basis (in the proportion that the Tenant's Allowance paid by Landlord and the
Excess Tenant Improvements Cost paid by Tenant bear to the Final Cost Quotation)
from time to time as the Tenant Improvements are constructed in the Premises.
Tenant shall pay its pro rata share of any 


*CONFIDENTIAL TREATMENT REQUESTED


                                       3.


<PAGE>   73
progress payments directly to Tenant's Contractor or subcontractors, as
appropriate, and Landlord shall pay its pro rata share of any progress payments
directly to Tenant's Contractor or subcontractors, as appropriate. Landlord
shall be entitled to suspend or terminate construction of the Tenant
Improvements and to declare Tenant in default in accordance with the terms of
the Lease, if payment by Tenant of Tenant's pro rata share of any progress
payment has not been received by Tenant's Contractor when due, as required
hereunder.

     (C)       TENANT IMPROVEMENT CONSTRUCTION.

          (1) All Tenant Improvements to be constructed or installed in the
Premises shall be performed by Tenant's Contractor in accordance with the
Approved Plans, subject to any changes agreed to by Landlord and Tenant in
writing. Landlord shall have no obligation to Tenant for defects in design,
workmanship or materials in connection with the Tenant Improvements. Any changes
to the Approved Plans shall require the written approval of Landlord and Tenant,
which approval shall not be unreasonably withheld, conditioned or delayed. All
such changes must be evidenced by a written change order executed by Landlord
and Tenant or their agent describing the change required in the Approved Plans,
and the cost of such changes shall be paid in accordance with the terms of this
Exhibit B.

          (2) Landlord shall coordinate construction of the Tenant Improvements
by Tenant's Contractor with the construction of the Base Building Improvements
by Landlord's Contractor in the most efficient manner reasonably possible for
the timely completion of the Base Building Improvements and the Tenant
Improvements. Landlord agrees to allow Tenant's Contractor access to the

          (3) Premises on or before the date to that is [...***...] days prior
to the Estimated Commencement Date (or such later date as may be reasonably
designated by Landlord) for the purpose of constructing the Tenant Improvements.
Landlord and Tenant shall each use good faith efforts to reasonably resolve any
issues or conflicts that may arise during the course of constructing the Tenant
Improvements and the Base Building Improvements. Entry by Tenant's Contractor in
accordance with this provision shall not constitute Tenant's occupancy of the
Premises under Paragraph 3 of the Lease; however, all terms and conditions of
the Lease shall apply to Tenant's Contractor's occupancy of and work within the
Premises.

     (D)       TERM COMMENCEMENT.

          (1) Notwithstanding anything in the Lease to the contrary, the
Commencement Date shall be the earliest of (a) the Commencement Date determined
in accordance with Paragraph 3 of the Lease or (b) the date the Commencement
Date would have occurred but for delays caused by Tenant or any employee, agent
or representative of Tenant ("Tenant Delays"), including, without limitation,
delays caused by (i) failure to furnish information in accordance with this
Exhibit B or Exhibit A of the Lease; (ii) Tenant's request for any special, long
lead time materials or installations as part of the Tenant Improvements or the
Tenant Requested Base Building Improvements; (iii) Tenant's changes in the
Approved Plans; (iv) any changes initiated by reason of the disapproval of any
plans or drawings or any cost proposals or authorizations 


*CONFIDENTIAL TREATMENT REQUESTED


                                       4.


<PAGE>   74
resulting in the preparation of revised plans, drawings, cost proposals or
authorizations beyond the second submission to Landlord for approval; (v) field
changes to construction work; (vi) the delivery, installation or completion of
the Tenant Improvements work performed by Tenant s Contractor beyond the
[...***...] period set forth in Section C.2 above; (vii)Tenant's request for any
Tenant Requested Base Building Improvements, as defined in Exhibit A of the
Lease; or (viii) any other act or omission of Tenant.

          (2) Except as may be otherwise specifically provided herein or in the
Lease, time periods for either party's performance under any provisions of this
Exhibit B, shall be extended for periods of time during which such party is
prevented due to circumstances beyond such party's control, including, without
limitation, strikes, embargoes, governmental regulations, delays in obtaining
permits or materials, acts of God, war, civil commotion or other strife ("Force
Majeure Events"). Each party shall use reasonable efforts to mitigate the effect
of any Force Majeure Event upon such party's performance hereunder.

          (3) If, for any reason other than Tenant Delays, Landlord cannot
deliver possession of the Premises to Tenant on the Estimated Commencement Date,
or perform any other covenant contained in this Exhibit B or in the Lease
related to the work described in this Exhibit B, the Lease shall not be void or
voidable nor shall Landlord be liable to Tenant for any loss or damage resulting
therefrom, nor shall such failure affect the obligations of Tenant under the
Lease or this Exhibit B, except as otherwise specifically provided in the Lease
and except that all Rent shall be abated during the period between the Estimated
Commencement Date and the date Landlord delivers possession.

     (E)       GENERAL.

          (1) All drawings, space plans, plans and specifications for any
improvements or installations in the Premises are expressly subject to
Landlord's prior written approval, which approval shall not be unreasonably
withheld, conditioned or delayed. Any approval by Landlord of any drawings,
plans or specifications prepared on behalf of Tenant including, without
limitation, any Preliminary Plans, Working Drawings or Approved Plans, or any
revisions thereto, shall not in any way bind Landlord, create any responsibility
or liability on the part of the Landlord for the completeness of the same, their
design sufficiency or compliance with applicable statutes, ordinances or
regulations or constitute a representation or warranty by Landlord as to the
adequacy or sufficiency of such drawings, plans or specifications, or the
improvements to which they relate, but such approval shall merely evidence the
consent of Landlord to such drawings, plans or specifications.


*CONFIDENTIAL TREATMENT REQUESTED


                                       5.


<PAGE>   75
          (2) Any failure by Tenant to pay any amounts due hereunder shall have
the same effect under the Lease as a failure to pay Rent and any failure by
Tenant to perform any of its other obligations hereunder shall be subject to
Paragraph 24 of the Lease.

INITIALS:

TENANT:

LANDLORD


                                       6.


<PAGE>   76
                                    EXHIBIT C

                                GUARANTY OF LEASE

        THIS GUARANTY OF LEASE ("Guaranty") is made as of __________________, by
________________________, a _______________________ corporation ("Guarantor"),
to("Landlord"), with reference to the following facts:

        A. Landlord has previously entered into a Lease Agreement ("Lease") with
_____________________, a ____________________ ("Tenant"), for certain premises
located at the Gateway Technology Center, South San Francisco, California, as
more particularly described in the Lease.

        B. Guarantor is willing to execute this Guaranty for the express and
intended purpose of inducing Landlord to replace existing Security granted
Landlord by Tenant under the Lease. Landlord would not agree to replace such
Security but for the execution and delivery of this Guaranty by Guarantor.

        C. Guarantor is affiliated with Tenant and will benefit from the
execution of the Lease. Guarantor is executing this Guaranty in consideration of
that anticipated benefit.

        NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged and agreed, Guarantor hereby agrees
as follows:

        1. GUARANTY. Guarantor does hereby absolutely and unconditionally,
jointly and severally guarantee to Landlord the prompt payment of all mounts
that Tenant, or any assignee of the Lease, may at any time owe under the Lease,
any extensions, renewals or modifications thereof, and further guarantees to
Landlord the full, prompt and faithful performance by Tenant, or any assignee of
the Lease, of each and all of the covenants, terms, and conditions of the Lease,
or any extensions, modifications or renewals thereof, to be hereafter performed
and kept by Tenant, or any assignee of the Lease (all such obligations of Tenant
under the Lease are referred to as "Tenant's Obligations"). Guarantor hereby
agrees to indemnify, defend and hold Landlord harmless from any and all
liabilities, losses, damages, costs and expenses (including but not limited to
reasonable attorneys' fees), by reason of a breach or default under the Lease by
Tenant or any assignee of the Lease.

        2. INDEPENDENT OBLIGATIONS. Guarantor's obligations hereunder are
independent of the obligations of Tenant, or any assignee of the Lease, and a
separate action or actions may be brought and prosecuted against Guarantor
whether or not action is brought against Tenant or any such assignee or whether
or not Tenant or any such assignee be joined in any such action or actions.

        3. RIGHTS OF LANDLORD. Guarantor authorizes Landlord, without notice or
demand and without affecting its liability hereunder, from time to time to (a)
extend, accelerate, or otherwise change the time for any payment provided for in
the Lease, or any covenant, term or condition of the Lease, impair or suspend
the Landlord's remedies or rights against Tenant in connection with the Lease,
and to consent to any assignment, subletting or reassignment of the Lease; (b)
take and hold security for any payment provided for in the Lease or for the


                                       1.


<PAGE>   77
performance of any covenant, term or condition of the Lease, or exchange, waive
or release any such security; and (c) apply such security and direct the order
or manner of sale thereof as Landlord in its discretion may determine. Landlord
may, without consideration to or consent of the Guarantor, assign this Guaranty,
the Lease, or the rents and other sums payable thereunder; provided however,
Landlord shall promptly after any such assignment notify Guarantor of such
action. Notwithstanding any termination, renewal, extension or holding over of
the Lease, this Guaranty shall continue until all of Tenant's Obligations have
been fully and completely performed by Tenant or any assignee of the Lease.

        Guarantor shall not be released by any act or event which might, but for
this provision of this Guaranty, be deemed a legal or equitable discharge of a
surety, or by reason of any waiver, extension, modification, forbearance or
delay or other act or omission of Landlord or its failure to proceed promptly or
otherwise as against Tenant or Guarantor, or by reason of any action taken or
omitted or circumstance which may or might vary the risk or affect the rights or
remedies of Guarantor as against Tenant, or by reason of any further dealings
between Tenant and Landlord, whether relating to the Lease or otherwise, and
Guarantor hereby expressly waives and surrenders any defense to its liability
hereunder based upon any of the foregoing acts, omissions, things, agreements,
waivers or any of them; it being the purpose and intent of this Guaranty that
the obligations of Guarantor hereunder are absolute and unconditional under any
and all circumstances.

        Guarantor further agrees that to the extent Tenant or Guarantor makes
any payment to Landlord in connection with. Tenant's Obligations and all or any
part of such payment is subsequently invalidated, declared to be fraudulent or
preferential, set aside or required to be repaid by Landlord or paid over to a
trustee, receiver or any other entity, whether under any bankruptcy act or
otherwise (any such payment is hereinafter referred to as a "Preferential
Payment"), then this Guaranty shall continue to be effective or shall be
reinstated, as the case may be, and, to the extent of such payment or repayment
by Landlord, Tenant's Obligations or part thereof intended to be satisfied by
such Preferential Payment shall be revived and continued in full force and
effect as if said Preferential Payment had not been made.

        4. WAIVER OF DEFENSES. Guarantor waives (a) any right to require
Landlord to (i) proceed against Tenant or any other person or entity; (ii)
proceed against or exhaust any security held from Tenant or Guarantor; (iii)
pursue any other remedy in Landlord's power which Guarantor cannot itself
pursue, and which would lighten its burden; (b) all statutes of limitations as a
defense to any action brought against Guarantor by Landlord to the fullest
extent permitted by law; (c) any defense based upon any legal disability of
Tenant, or any assignee of the Lease, or any discharge or limitation of the
liability of Tenant, or any assignee of the Lease, to Landlord, whether
consensual or arising by operation of law or any bankruptcy, reorganization,
receivership, insolvency, or debtor-relief proceeding, or from any other cause;
(d) presentment, demand, protest, and notice of any kind, except as specifically
provided below; and (e) any defense based upon or arising out of any defense
which Tenant, or any assignee of the Lease, may have to the payment or
performance of any part of Tenant's Obligations. Guarantor waives all demands
upon and notices to Tenant, or any assignee of the Lease, and to Guarantor
(except as specifically provided below), including demands for performance,
notices of non-performance, notices of non-payment and notice of acceptance of
this Guaranty. Landlord shall give three (3) days prior written notice. to
Guarantor of Landlord's demand for Guarantor to 


                                       2.


<PAGE>   78
perform under this Guaranty and Guarantor hereby agrees to so perform within
said time period. If Guarantor fails to so perform within said time period,
Landlord may enforce this Guaranty in accordance with all of Landlord's rights
and remedies provided in this Guaranty, at law or in equity. Notwithstanding
anything in the Guaranty to the contrary, failure by Landlord to give prior
notice of demand shall in no way relieve Guarantor of any of its obligations
under this Guaranty.

        5.     WAIVER OF SUBROGATION.

               (a) Notwithstanding any other provision of this Guaranty to the
contrary, until the obligations of Tenant under the Lease are fully performed
and paid, Guarantor hereby waives any claims or other rights which Guarantor may
now have or hereafter acquire against Tenant or any other guarantor of all or
any of Tenant's Obligations, which claims or other rights arise from the
existence or performance of Guarantor's obligations under this Guaranty or the
Lease (all such claims and rights are referred to as "Guarantor's Conditional
Rights"), including, without limitation, any right of subrogation,
reimbursement, exoneration, contribution, or indemnification, any right to
participate in any claim or remedy of Landlord against Tenant or any collateral
which Landlord now has or hereafter acquires, whether or not such claim, remedy
or right arises in equity or under contract, statute or common law, by any
payment made hereunder or otherwise, including without limitation, the right to
take or receive from Tenant, directly or indirectly, in cash or other property
or by setoff or in any other manner, payment or security on account of such
claim or other rights. If, notwithstanding the foregoing provisions, any amount
shall be paid to Guarantor on account of any Guarantor's Conditional Rights and
either (i) such amount is paid to Guarantor at any time when Tenant's
Obligations shall not have been paid or performed in full, or (ii) regardless of
when such amount is paid to Guarantor, any payment made by Tenant to Landlord is
at any time determined to be a Preferential Payment, then such amount paid to
Guarantor shall be held in trust for the benefit of Landlord and shall forthwith
be paid to Landlord to be credited and applied upon Tenant's Obligations,
whether matured or unmatured, in such order as Landlord, in its sole and
absolute discretion, shall determine.

               (b) To the extent that any of the provisions of subsection (a) of
the above Section shall not be enforceable, Guarantor agrees that until such
time as Tenant's Obligations have been paid and performed in full and the period
of time has expired during which any payment made by Tenant or Guarantor to
Landlord may be determined to be a Preferential Payment, Guarantor's Conditional
Rights to the extent not validly waived shall be subordinate to Landlord's right
to full payment and performance of Tenant's Obligations, and Guarantor shall not
enforce Guarantor's Conditional Rights during such period.

        6. COSTS AND EXPENSES. If Guarantor fails to perform any of its
obligations under this Guaranty or if any dispute arises between the parties
hereto concerning the meaning or interpretation of any provision of this
Agreement, then the defaulting party or the party not prevailing in such
dispute, as the case may be, shall pay any and all costs and expenses incurred
by the other party on account of such default and/or in enforcing or
establishing its rights hereunder, including, without limitation, court costs
and reasonable attorneys' fees and disbursements. Any such attorneys' fees and
other expenses incurred by either party in enforcing a judgment in its favor
under this Agreement shall be recoverable separately from and 


                                       3.


<PAGE>   79
in addition to any other amount included in such judgment, and such attorneys'
fees obligation is intended to be severable from the other provisions of this
Agreement and to survive and not be merged into any such judgment.

        7. NOTICES. Any notice, demand or request by Landlord to Guarantor shall
be in writing and shall be deemed to have been duly given or made if mailed by
certified or registered mail addressed to Guarantor at its address set forth
below its signature.

        8. DELAY; CUMULATIVE REMEDIES. No delay or failure by Landlord to
exercise any right or remedy against Tenant or Guarantor will be construed as a
waiver of that right or remedy. All remedies of Landlord against Tenant and
Guarantor are cumulative.

        9. MISCELLANEOUS.

               (a) This Guaranty shall bind Guarantor, its successors and
assigns, and shall inure to the benefit of Landlord and its successors and
assigns.

               (b) The invalidity or unenforceability of any one or more
provisions of this Guaranty will not affect any other provision.

               (c) This Guaranty and each and every term and provision thereof
shall be construed in accordance with the laws of the State of California.

        IN WITNESS WHEREOF, Guarantor has executed this instrument on the day
and year first above written.



                    GUARANTOR:      ________________________________________ ,
                                    a_____________________________corporation



                                    By:_______________________________________

                                    Print Name:_______________________________

                                    Its:______________________________________



                      ADDRESS:      ________________________________________

                                    ________________________________________

                                    ________________________________________


                                       4.


<PAGE>   80
                                    EXHIBIT D

                   COMMENCEMENT AND EXPIRATION DATE MEMORANDUM

        LANDLORD:     ___________________________________

        TENANT:       COULTER PHARMACEUTICAL, INC.

        LEASE DATE:   __________________________,1997

        PREMISES:            Located at ____________________, California

        Tenant hereby accepts the Premises as being in the condition required
under the Lease, with all Tenant improvements completed (except for minor
punchlist items which Landlord agrees to complete).

        The Commencement Date of the Lease is hereby established as
_______________,1997 and the Expiration Date is _______________________, ____.

                             TENANT: COULTER PHARMACEUTICAL, INC.,
                                     a Delaware corporation

                                     By:_______________________________

                                     Print Name:_______________________

                                     Its:______________________________

Approved and Agreed:

LANDLORD:

____________________________________

a___________________________________



By:_________________________________

Print Name:_________________________

Its:________________________________

INITIALS:

TENANT:

LANDLORD


                                       1.


<PAGE>   81
                                    EXHIBIT E

                              RULES AND REGULATIONS

        This exhibit, entitled "Rules and Regulations," is and shall constitute
Exhibit E to the Lease Agreement, dated as of the Lease Date, by and between
Landlord and Tenant for the Premises. The terms and conditions of this Exhibit E
are hereby incorporated into and are made a part of the Lease. Capitalized terms
used, but not otherwise defined, in this Exhibit E have the meanings ascribed to
such terms in the Lease.

          (1) Tenant shall not use any method of heating or air conditioning
other than that supplied by Landlord without the prior written consent of
Landlord, which consent shall not to be unreasonably withheld, conditioned or
delayed.

          (2) All window coverings installed by Tenant and visible from the
outside of the building require the prior written approval of Landlord which
approval shall not to be unreasonably withheld, conditioned or delayed.

          (3) Tenant shall not use, keep or permit to be used or kept any foul
or noxious gas or substance or any flammable or combustible materials on or
around the Premises, except to the extent that Tenant is permitted to use the
same under the terms of Paragraph 32 of the Lease.

          (4) Tenant shall not alter any lock or install any new locks or bolts
on any door at the Premises without the prior written consent of Landlord, which
consent shall not to be unreasonably withheld, conditioned or delayed.

          (5) Tenant shall not make any duplicate keys without the prior written
consent of Landlord, which consent shall not to be unreasonably withheld,
conditioned or delayed.

          (6) Tenant shall park motor vehicles in parking areas designated by
Landlord except for loading and unloading. During those periods of loading and
unloading, Tenant shall not unreasonably interfere with traffic flow around the
Building or the Project and loading and unloading areas of other tenants.

          (7) Tenant shall not disturb, solicit or canvas any tenant or other
occupant of the Building or Project and shall cooperate to prevent same.

          (8) No person shall go on the roof without Landlord's permission.

          (9) Business machines and mechanical equipment belonging to Tenant
which cause noise or vibration that may be transmitted to the structure of the
Building, to such a degree as to be objectionable to Landlord or other tenants,
shall be placed and maintained by Tenant, at Tenant's expense, on vibration
isolators or in noise-dampening housing or other devices sufficient to eliminate
noise or vibration.

          (10) All goods, including material used to store goods, delivered to
the Premises of Tenant shall be immediately moved into the Premises and shall
not be left in parking or receiving areas overnight.


                                       1.


<PAGE>   82
          (11) Tenant is responsible for the storage and removal of all trash
and refuse. All such trash and refuse shall be contained in suitable receptacles
stored behind screened enclosures at locations approved by Landlord.

          (12) Tenant shall not store or permit the storage or placement of
goods or merchandise in or around the common areas surrounding the Premises. No
displays or sales or merchandise shall be allowed in the parking lots or other
common areas.

          (13) Tenant shall not permit any animals, including but not limited
to, any household pets, to be brought or kept in or about the Premises, the
Building, the Project or any of the common areas which would violate applicable
Laws or constitute a nuisance to the Premises, the Building or the Project.

INITIALS:

TENAN:

LANDLORD


                                       2.


<PAGE>   83
                                    EXHIBIT F

                   HAZARDOUS MATERIALS DISCLOSURE CERTIFICATE

        Your cooperation in this matter is appreciated. Initially, the
information provided by you in this Hazardous Materials Disclosure Certificate
is necessary for the Landlord to evaluate your proposed uses of the premises
(the "Premises") and to determine whether to enter into a lease agreement with
you as tenant. If a lease agreement is signed by you and the Landlord (the
"Lease Agreement"), on an annual basis in accordance with the provisions of
Paragraph 32 of the Lease Agreement, you are to provide an update to the
information initially provided by you in this certificate. Any questions
regarding this certificate should be directed to, and when completed, the
certificate should be delivered to:

Landlord:__________________________________________

               c/o_________________________________

               ____________________________________

               Phone: (___)________________________

Name of (Prospective) Tenant: Coulter Pharmaceutical, Inc.

Mailing Address:________________________________________________________________

________________________________________________________________________________


Contact Person, Title and Telephone Number(s):__________________________________

Contact Person for Hazardous Waste Materials Management and Manifests and 
Telephone Number(s):____________________________________________________________

Address of (Prospective) Premises:______________________________________________

Length of (Prospective) initial Term:___________________________________________

________________________________________________________________________________


                                       1.


<PAGE>   84
1.      GENERAL INFORMATION:

        Describe the proposed operations to take place in, on, or about the
Premises, including, without limitation, principal products processed,
manufactured or assembled, and services and activities to be provided or
otherwise conducted. Existing tenants should describe any proposed changes to
on-going operations.

________________________________________________________________________________

________________________________________________________________________________


2.      USE, STORAGE AND DISPOSAL OF HAZARDOUS MATERIALS

        2.1     Will any Hazardous Materials (as hereinafter defined) be used,
                generated, treated, stored or disposed of in, on or about the
                Premises? Existing tenants should describe any Hazardous
                Materials which continue to be used, generated, treated, stored
                or disposed of in, on or about the Premises.

                Wastes                         Yes 0                No 0

                Chemical Products              Yes 0                No 0

                Other                          Yes 0                No 0

                If Yes is marked, please explain:

        2.2     If Yes is marked in Section 2.1, attach a list of any Hazardous
                Materials to be used, generated, treated, stored or disposed of
                in, on or about the Premises, including the applicable hazard
                class and an estimate of the quantities of such Hazardous
                Materials to be present on or about the Premises at any given
                time; estimated annual throughput; the proposed location(s) and
                method of storage (excluding nominal mounts of ordinary
                household cleaners and janitorial supplies which are not
                regulated by any Environmental Laws, as hereinafter defined);
                and the proposed location(s) and method(s) of treatment or
                disposal for each Hazardous Material, including, the estimated
                frequency, and the proposed contractors or subcontractors.
                Existing tenants should attach a list setting forth the
                information requested above and such list should include actual
                data from on-going operations and the identification of any
                variations in such information from the prior year's
                certificate.

3.      STORAGE TANKS AND SUMPS

        3.1     Is any above or below ground storage or treatment of gasoline,
                diesel, petroleum, or other Hazardous Materials in tanks or
                sumps proposed in, on or about the Premises? Existing tenants
                should describe any such actual or proposed activities.

                 Yes 0                                    No 0


                                       2.


<PAGE>   85
        If yes, please explain:

4.      WASTE MANAGEMENT

        4.1     Has your company been issued an EPA Hazardous Waste Generator
                I.D. Number? Existing tenants should describe any additional
                identification numbers issued since the previous certificate.

                Yes 0                                    No 0

        4.2     Has your company filed a biennial or quarterly reports as a
                hazardous waste generator? Existing tenants should describe any
                new reports filed.

                Yes 0                                    No 0

               If yes, attach a copy of the most recent report filed.

5.      WASTEWATER TREATMENT AND DISCHARGE

        5.1     Will your company discharge wastewater or other wastes to:

           ____ storm drain?     ____ sewer?

           ____ surface water?   _____ no wastewater or other wastes discharged.

               Existing tenants should indicate any actual discharges. If so,
               describe the nature of any proposed or actual discharge(s).

        5.2     Will any such wastewater or waste be treated before discharge?

                Yes 0                                    No 0

                If yes, describe the type of treatment proposed to be conducted.
                Existing tenants should describe the actual treatment conducted.

6.      AIR DISCHARGES

        6.1     Do you plan for any air filtration systems or stacks to be used
                in your company's operations in, on or about the Premises that
                will discharge into the air; and will such air emissions be
                monitored? Existing tenants should indicate whether or not
                there are any such air filtration systems or stacks in use in,
                on or about the Premises which discharge into the air and
                whether such air emissions are being monitored.

                Yes 0                                    No 0

                If yes, please describe:


                                       3.


<PAGE>   86
        6.2     Do you propose to operate any of the following types of
                equipment, or any other equipment requiring an air emissions
                permit? Existing tenants should specify any such equipment being
                operated in, on or about the Premises.

                ____ Spray booth(s)      ____ Incinerator(s)

                ____ Dip tank(s)         ____ Other (Please describe)
 
                ____ Drying oven(s)      ____ No Equipment Requiring Air Permits

               If yes, please describe: _______________________________________

               ________________________________________________________________

        6.3     Please describe (and submit copies of with this Hazardous
                Materials Disclosure Certificate) any reports you have flied in
                the past [thirty-six] months with any governmental or
                quasi-governmental agencies or authorities related to air
                discharges or clean air requirements and any such reports which
                have been issued during such period by any such agencies or
                authorities with respect to you or your business operations.

7.      HAZARDOUS MATERIALS DISCLOSURES

        7.1     Has your company prepared or will it be required to prepare a
                Hazardous Materials management plan ("Management Plan") or
                Hazardous Materials Business Plan and Inventory ("Business
                Plan") pursuant to Fire Department or other governmental or
                regulatory agencies' requirements? Existing tenants should
                indicate whether or not a Management Plan is required and has
                been prepared.

                Yes 0                                    No 0

               If yes, attach a copy of the Management Plan or Business Plan.
        Existing tenants should attach a copy of any required updates to the
        Management Plan or Business Plan.

        7.2     Are any of the Hazardous Materials, and in particular chemicals,
                proposed to be used in your operations in, on or about the
                Premises listed or regulated under Proposition 65? Existing
                tenants should indicate whether or not there are any new
                Hazardous Materials being so used which are listed or regulated
                under Proposition 65.

                Yes 0                                    No 0

                If yes, please explain:_________________________________________

                ________________________________________________________________


                                       4.


<PAGE>   87
8.      ENFORCEMENT ACTIONS AND COMPLAINTS

        8.1     With respect to Hazardous Materials or Environmental Laws, has
                your company ever been subject to any agency enforcement
                actions, administrative orders, or consent decrees or has your
                company received requests for information, notice or demand
                letters, or any other inquiries regarding its operations?
                Existing tenants should indicate whether or not any such
                actions, orders or decrees have been, or are in the process of
                being, undertaken or if any such requests have been received.

                Yes 0                                    No 0

                If yes, describe the actions, orders or decrees and any
                continuing compliance obligations imposed as a result of these
                actions, orders or decrees and also describe any requests,
                notices or demands, and attach a copy of all such documents.
                Existing tenants should describe and attach a copy of any new
                actions, orders, decrees, requests, notices or demands not
                already delivered to Landlord pursuant to the provisions of
                Paragraph 32 of the Lease Agreement.

        8.2     Have there ever been, or are there now pending, any lawsuits
                against your company regarding any environmental or health and
                safety concerns?

                Yes 0                                    No 0

                If yes, describe any such lawsuits and attach copies of the
                complaint(s), cross-complaint(s), pleadings and other documents
                related thereto as requested by Landlord. Existing tenants
                should describe and attach a copy of any new complaint(s),
                cross-complaint(s), pleadings and other related documents not
                already delivered to Landlord pursuant to the provisions of
                Paragraph 32 of the Lease Agreement.

        8.3     Have there been any problems or complaints from adjacent
                tenants, owners or other neighbors at your company's current
                facility with regard to environmental or health and safety
                concerns? Existing tenants should indicate whether or not there
                have been any such problems or complaints from adjacent tenants,
                owners or other neighbors at, about or near the Premises and the
                current status of any such problems or complaints.

                Yes 0                                    No 0

                If yes, please describe. Existing tenants should describe any
                such problems or complaints not already disclosed to Landlord
                under the provisions of the signed Lease Agreement and the
                current status of any such problems or complaints.

9.      PERMITS AND LICENSES

        9.1     Attach copies of all permits and licenses issued to your company
                with respect to its proposed operations in, on or about the
                Premises, including, without limitation, any Hazardous Materials
                permits, wastewater discharge permits, air emissions 


                                       5.


<PAGE>   88
                permits, and use permits or approvals. Existing tenants should
                attach copies of any new permits and licenses as well as any
                renewals of permits or licenses previously issued.

                As used herein, "Hazardous Materials" shall mean and include any
                substance that is or contains (a) any "hazardous substance" as
                now or hereafter defined in Section 101 (I 4) of the
                Comprehensive Environmental Response, Compensation, and
                Liability Act of 1980, as amended ("CERCLA") (42 U.S.C. Section
                9601 et seq.) or any regulations promulgated under CERCLA; (b)
                any "hazardous waste" as now or hereafter defined in the
                Resource Conservation and Recovery Act, as amended ("RCRA") (42
                U.S.C. Section 6901 et seq.) or any regulations promulgated
                under RCRA; (c) any substance now or hereafter regulated by the
                Toxic Substances Control Act, as amended ("TSCA") (15 U.S.C.
                Section 2601 et seq.) or any regulations promulgated under TSCA;
                (d) petroleum, petroleum by-products, gasoline, diesel fuel, or
                other petroleum hydrocarbons; (e) asbestos and
                asbestos-containing materials, in any form, whether friable or
                non-friable; (f) polychlorinated biphenyls; (g) lead and
                lead-containing materials; or (h) any additional substance,
                material or waste (A) the presence of which on or about the
                Premises (i) requires reporting, investigation or remediation
                under any Environmental Laws (as hereinafter defined), (ii)
                causes or threatens to cause a nuisance on the Premises or any
                adjacent property or poses or threatens to pose a hazard to the
                health or safety of persons on the Premises or any adjacent
                property, or (iii) which, if it emanated or migrated from the
                Premises, could constitute a trespass, or (B) which is now or is
                hereafter classified or considered to be hazardous or toxic
                under any Environmental Laws; and "Environmental Laws" shall
                mean and include (a) CERCLA, RCRA and TSCA; and (b) any other
                federal, state or local laws, ordinances, statutes, codes,
                rules, regulations, orders or decrees now or hereinafter in
                effect relating to (i) pollution, (ii) the protection or
                regulation of human health, natural resources or the
                environment, (iii) the treatment, storage or disposal of
                Hazardous Materials, or (iv) the emission, discharge, release or
                threatened release of Hazardous Materials into the environment.

                The undersigned hereby acknowledges and agrees that this
                Hazardous Materials Disclosure Certificate is being delivered to
                Landlord in connection with the evaluation of a Lease Agreement
                and, if such Lease Agreement is executed, will be attached
                thereto as an exhibit. The undersigned further acknowledges and
                agrees that if such Lease Agreement is executed, this Hazardous
                Materials Disclosure Certificate will be updated from time to
                time in accordance with Paragraph 32 of the Lease Agreement. The
                undersigned further acknowledges and agrees that the Landlord
                and its partners, lenders and representatives may, and will,
                rely upon the statements, representations, warranties, and
                certifications made herein and the truthfulness thereof in
                entering into the Lease Agreement and the continuance thereof
                throughout the term, and any renewals thereof, of the Lease
                Agreement. I [print name] ____________________, acting with full
                authority to bind the (proposed) Tenant and on behalf of the
                (proposed) Tenant, certify, represent and warrant that the
                information contained in this certificate is true and correct.


                                       6.


<PAGE>   89
(PROSPECTIVE) TENANT:



By:______________________________

Title:___________________________

Date:____________________________

INITIALS:

TENANT:

LANDLORD


                                       7.


<PAGE>   90
                                    EXHIBIT G

                                 EXPANSION LAND

                                 [GRAPHIC - MAP]


                                       1.


<PAGE>   91
                                    EXHIBIT H

                              INITIAL WINDOW DATES

CONDITION                                                    INITIAL WINDOW DATE

Certificate from Landlord's Architect that the foundation of     [...***...]
the Building has been completed.

Certificate from Landlord's Architect that the construction of   [...***...] 
the Building has progressed to a "Water Tight Shell"

INITIALS:

TENANT:

LANDLORD


                                       1.


<PAGE>   92
                                    EXHIBIT I

                                TENANT'S PROPERTY

Laboratory related furniture and equipment including:

        benches and tables
        shelving
        sinks
        biosafety, laminar flow and fume hoods 
        cages/fencing 
        DI water system
        emergency generator 
        vacuum pumps 
        compressed air 
        nitrogen manifold

Office related furniture and equipment including:

        open office partitions 
        telephone and network equipment 
        reception desk
        lobby furniture 
        lobby display cases 
        appliances
        security system control panels, sensors, and cctv equipment
        interior signage

INITIALS:

TENANT:

LANDLORD


                                       1.


<PAGE>   93
                                    EXHIBIT J

                               MEMORANDUM OF LEASE

RECORDING REQUESTED BY AND
WHEN RECORDED RETURN TO:

Cooley Godward, LLP
3000 El Camino Real
Palo Alto, California 94306
Attention: Anna B. Pope, Esq.

                               MEMORANDUM OF LEASE

        THIS MEMORANDUM OF LEASE is executed as of ______________, by and
between HMS GATEWAY OFFICE, L.P., a Delaware limited partnership ("Landlord"),
and COULTER PHARMACEUTICAL, INC., a Delaware corporation ("Tenant"). Landlord
has previously leased to Tenant a portion of that certain real property
described on Exhibit A attached hereto and incorporated herein by reference,
consisting of the building commonly known as 600 Gateway Boulevard located in
South San Francisco, California, commencing on ________________ and terminating
on _________________, on the terms and conditions set forth in that certain
Lease between Landlord and Tenant dated as of November __, 1997 (the "Off Record
Lease"). Landlord has also granted to Tenant (i) options to renew the term of
the Lease for two (2) additional periods of [...***...]
 each, (ii) a right to expand the premises being [eased by Tenant and (iii) a
right of first offer with respect to the premises being leased by Tenant, all on
terms and conditions of the Off Record Lease.

        IN WITNESS WHEREOF, the undersigned have executed this Memorandum of
Lease so that third parties might have notice of the lease by Landlord and
Tenant herein.

                           Landlord:     HMS Gateway Office, L.P.
                                         a Delaware limited liability company

                                  By:    Hines Interests Limited Partnership,
                                         General Partner

                                         By:    Hines Holdings, Inc.
                                                General Partner

                                                By:__________________________

                                                Name:________________________

                                                Its:_________________________



* Confidential Treatment Requested.

                                       1.


<PAGE>   94
                                       Tenant:  COULTER PHARMACEUTICAL, INC.
                                                a Delaware limited 
                                                liability company



                                                By:__________________________

                                                Name:________________________

                                                Its:_________________________







                                       2.