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

Exhibit 10.1
 
MARINA VILLAGE

LEASE
 
BSREP MARINA VILLAGE OWNER LLC,
a Delaware limited liability company,

as Landlord,

and

BIOTIME, INC.,
a California corporation,

as Tenant
 
 
MARINA VILLAGE
[Biotime]

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

INDEX
 
Page(s)
 
SUMMARY OF BASIC LEASE INFORMATION
iv

                                                                                                          

LEASE          
ARTICLE 1
PROJECT, BUILDING AND PREMISES
1
ARTICLE 2
LEASE TERM
2
ARTICLE 3
BASE RENT
2
ARTICLE 4
ADDITIONAL RENT
3
ARTICLE 5
USE OF PREMISES
9
ARTICLE 6
SERVICES AND UTILITIES
9
ARTICLE 7
REPAIRS
10
ARTICLE 8
ADDITIONS AND ALTERATIONS
11
ARTICLE 9
COVENANT AGAINST LIENS
12
ARTICLE 10
INDEMNIFICATION AND INSURANCE
12
ARTICLE 11
DAMAGE AND DESTRUCTION
14
ARTICLE 12
CONDEMNATION
15
ARTICLE 13
COVENANT OF QUIET ENJOYMENT
15
ARTICLE 14
ASSIGNMENT AND SUBLETTING
16
ARTICLE 15
SURRENDER; OWNERSHIP AND REMOVAL OF TRADE FIXTURES
18
ARTICLE 16
HOLDING OVER
18
ARTICLE 17
ESTOPPEL CERTIFICATES
18
ARTICLE 18
SUBORDINATION
19
ARTICLE 19
TENANT'S DEFAULTS; LANDLORD'S REMEDIES
19
ARTICLE 20
SECURITY DEPOSIT
21
ARTICLE 21
COMPLIANCE WITH LAW
22
ARTICLE 22
ENTRY BY LANDLORD
22
ARTICLE 23
PARKING
22
ARTICLE 24
MISCELLANEOUS PROVISIONS
23

 

EXHIBITS      
A-1
OUTLINE OF 1010 PREMISES
A-2
OUTLINE OF 1020 PREMISES
A-3
SITE PLAN OF PROJECT
A-4
DEPICTION OF 1010 OFFICE SPACE AND 1010 LAB SPACE
B
TENANT WORK LETTER
C
AMENDMENT TO LEASE
D
RULES AND REGULATIONS
E
DEPICTION OF GENERATOR SITE
EXTENSION OPTION RIDER

 

 (i)
MARINA VILLAGE
[Biotime]

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

Additional Rent
3
Alterations
11
Amendment
Exhibit C
Base Rent
2
Base, Shell and Core
Exhibit B
BOMA
2
Brokers
26
Building Warranty Period
10
Business Affiliate
17
Calendar Year
3
Construction
26
Construction Drawings
Exhibit B
Contract
Exhibit B
Coordination Fee
Exhibit B
Cost Pools
4
Engineers
Exhibit B
Estimate
7
Estimate Statement
7
Estimated Excess
7
Excess
6
Exercise Date
Rider
Exercise Notice
Rider
Expense Base Year
3
Expense Year
3
Extension Rider
Rider
Fair Market Rental Rate
Rider
Final Costs
Exhibit B
Final Costs Statement
Exhibit B
Final Space Plan
Exhibit B
Final Working Drawings
Exhibit B
Force Majeure
25
Hazardous Material
9
Initial Allowance
Exhibit B
Interest Notice
Rider
Interest Rate
8
Landlord
1
Landlord Parties
12
Lease
1
Lease Commencement Date
2
Lease Expiration Date
2
Lease Term
2
Lease Year
2
Notices
25
Operating Expenses
3
Option Rent
Rider
Option Rent Notice
Rider
Option Term
Rider
Other Buildings
7
Other Existing Buildings
1
Over-Allowance Amount
Exhibit B
Premises
1
Project
1
Proposition 13
5
Rent
3
rentable square feet
2
Security Deposit
21
Signage Monument
24
Statement
6
Subject Space
16
Subleasing Costs
16
Summary
iv
Systems and Equipment
5
Tax Expense Base Year
5
Tax Expenses
5
Tenant
1
Tenant Improvement Allowance Items
Exhibit B
Tenant Improvements
Exhibit B
Tenant Work Letter
Exhibit B
Tenant's 1010 Share
6
Tenant's 1020 Share
6
Tenant's Agents
Exhibit B
Transfer Notice
16

 

 (ii)
MARINA VILLAGE
[Biotime]

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

Transfer Premium
16
Transfers
16
Utilities Base Year
6
Utilities Costs
6
Wi-Fi Network
12

 

 (iii)
MARINA VILLAGE
[Biotime]

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

SUMMARY OF BASIC LEASE INFORMATION
 
This Summary of Basic Lease Information ("Summary") is hereby incorporated into
and made a part of the attached Lease.  Each reference in the Lease to any term
of this Summary shall have the meaning as set forth in this Summary for such
term.  In the event of a conflict between the terms of this Summary and the
Lease, the terms of the Lease shall prevail.  Any capitalized terms used herein
and not otherwise defined herein shall have the meaning as set forth in the
Lease.
 
TERMS OF LEASE
(References are to the Lease)
DESCRIPTION
   
1.                  Date:
December 10, 2015
   
2.                  Landlord:
BSREP MARINA VILLAGE OWNER LLC,
a Delaware limited liability company
   
3.                  Address of Landlord (Section 24.19):
For all Notices:
 
c/o Brookfield Property Group
Brookfield Place, Suite 300
181 Bay Street, P.O. Box 762
Toronto, Ontario M5J 2T3
Attention:  Thomas Diamond
Email:
 
with a copy to:
 
c/o Brookfield Property Group
Brookfield Place, 15th Floor
250 Vesey Street,
New York, NY 10281-1023
Attention:  Steven Ganeless
Email: 
 
For Payments by Check via USPS:
 
BSREP MARINA VILLAGE OWNER LLC
P.O. Box 398059
San Francisco, CA  94139-8059
 
For Payments by Check via Overnight Delivery:
 
BSREP MARINA VILLAGE OWNER LLC
DEPT# 38059
3440 Walnut Avenue, Bldg. A, Window H
Fremont, CA  94538
 
For Payments by Wire or ACH:
 
Wells Fargo Bank, N.A.
San Francisco, CA
ABA # 121 000 248
Acct # 4940840143
Acct Name:  BSREP MARINA VILLAGE OWNER LLC
   
4.                  Tenant:
BIOTIME, INC.,
a California corporation
   
5.                  Address of Tenant (Section 24.19):
1301 Harbor Bay Parkway
Alameda, California 94502
Attention:  Floyd Kastning
(Prior to Lease Commencement Date)

 

 (iv)
MARINA VILLAGE
[Biotime]

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

TERMS OF LEASE
(References are to the Lease)
DESCRIPTION
     
and
 
1010 Atlantic Avenue, Suite 102
Alameda, California  94501
Attention:  Floyd Kastning
 
(After Lease Commencement Date)
   
6.                  Premises (Article 1):
     
6.1                Premises:
Approximately 30,795 rentable square feet of space comprised of:  (i)
approximately 22,303 rentable square feet of space commonly known as Suite 102
and located on the first (1st) floor of the 1010 Building (as defined below), as
depicted on Exhibit A-1 attached hereto and commonly known as Suite 102 (the
"1010 Premises"); and (ii) approximately 8,492 rentable square feet of space
commonly known as Suite 100 and located on the first (1st) floor of the 1020
Building (as defined below), as depicted on Exhibit A-2 attached hereto and
commonly known as Suite 100 (the "1020 Premises", and together with the 1010
Premises, collectively, the "Premises").
   
6.2                Building:
The 1010 Premises are located in the building whose address is 1010 Atlantic
Avenue, Alameda, California (the "1010 Building").  The 1020 Premises are
located in the building whose address is 1020 Atlantic Avenue, Alameda,
California (the "1020 Building", and together with the 1010 Building,
collectively, the "Buildings").
   
7.                  Term (Article 2):
     
7.1                Lease Term:
Seven (7) years.
   
7.2                Lease Commencement Date:
The earlier to occur of (i) the date Tenant commences business operations in all
or any portion of the Premises, or (ii) June 1, 2016.
   
7.3                Lease Expiration Date:
The last day of the month in which the seven (7) year anniversary of the Lease
Commencement Date occurs.
   
7.4                Extension Option (Extension Option Rider):
One (1) five (5) year option to extend the initial Lease Term, pursuant to the
Extension Option Rider attached to the Office Lease.
   
8.                  Base Rent (Article 3):
 

 
Lease Year
   
Annual
Base Rent
   
Monthly
Installment
of Base Rent
   
Monthly Base Rental Rate
per Rentable Square Foot
of Premises
 
1
   
$
776,034.00
   
$
64,669.50
   
$
2.10
 
2
   
$
798,206.40
   
$
66,517.20
   
$
2.16
 
3
   
$
824,074.20
   
$
68,672.85
   
$
2.23
 
4
   
$
846,246.60
   
$
70,520.55
   
$
2.29
 
5
   
$
872,114.40
   
$
72,676.20
   
$
2.36
 
6
   
$
897,982.20
   
$
74,831.85
   
$
2.43
 
7
   
$
927,545.40
   
$
77,295.45
   
$
2.51
 

 
9.                  Additional Rent (Article 4):
     
9.1                Expense Base Year:
Calendar year 2016.
   
9.2                Tax Expense Base Year:
Calendar year 2016.
   
9.3                Utilities Base Year:
Calendar year 2016.

 

 (v)
MARINA VILLAGE
[Biotime]

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

TERMS OF LEASE
(References are to the Lease)
DESCRIPTION
   
9.4                Tenant's Share of Operating Expenses, Tax Expenses and
Utilities Costs for the 1010 Building:
50.69% (22,303 rentable square feet within the 1010 Premises/44,000 rentable
square feet within the 1010 Building).
   
9.5                Tenant's Share of Operating Expenses, Tax Expenses and
Utilities Costs for the 1020 Building:
33.15% (8,492 rentable square feet within the 1020 Premises/25,616 rentable
square feet within the 1020 Building).
   
10.            Security Deposit (Article 20):
$846,862.50, subject to reduction pursuant to Article 20.
   
11.            Brokers (Section 24.25):
CBRE, Inc. representing Landlord, and Cresa, representing Tenant.
   
12.            Parking (Article 23):
One hundred eight (108) unreserved parking passes (i.e., 3.4 unreserved parking
spaces for every 1,000 rentable square feet of the Premises).
   
13.            Tenant Improvement Allowance (Exhibit B):
Initial Allowance:  Up to $1,385,775.00 Additional Allowance:  Up to $307,950.00

 

 (vi)
MARINA VILLAGE
[Biotime]

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

LEASE
 
This Lease, which includes the preceding Summary and the exhibits attached
hereto and incorporated herein by this reference (the Lease, the Summary and the
exhibits to be known sometimes collectively hereafter as the "Lease"), dated as
of the date set forth in Section 1 of the Summary, is made by and between BSREP
MARINA VILLAGE OWNER LLC, a Delaware limited liability company ("Landlord"), and
BIOTIME, INC., a California corporation ("Tenant").
 
ARTICLE 1
 
PROJECT, BUILDINGS AND PREMISES
 
1.1           Project, Buildings and Premises.
 
1.1.1            Premises.  Upon and subject to the terms, covenants and
conditions hereinafter set forth in this Lease, Landlord hereby leases to Tenant
and Tenant hereby leases from Landlord the premises described in Section 6.1 of
the Summary (the "Premises"), which Premises are located in the Buildings (as
defined in Section 6.2 of the Summary) and located within the Project (as
defined below).  The floor plans of the Premises are attached hereto as Exhibits
A-1 and A-2.
 
1.1.2            Buildings and Project.  The Buildings are part of a
multi-building commercial project known as "Marina Village" and located on the
approximately 200-acre site on the estuary side of the island of Alameda.  The
term "Project" as used in this Lease, shall mean, collectively: (i) the
Buildings; (ii) the other existing buildings located within such 200-acre site
(collectively, the "Other Existing Buildings"); (iii) the surface parking areas
servicing the Buildings and the Other Existing Buildings and located within such
200-acre site (collectively, the "Parking Facilities"); (iv) any outside plaza
areas, walkways, driveways, courtyards, public and private streets,
transportation facilitation areas and other improvements and facilities now or
hereafter constructed surrounding and/or servicing the Buildings and/or the
Other Existing Buildings, which are designated from time to time by Landlord
(and/or any other owners of Marina Village) as common areas appurtenant to or
servicing the Buildings, the Other Existing Buildings and any such other
improvements; (v) any additional buildings, improvements, facilities and common
areas which Landlord (any other owners of Marina Village and/or any common area
association formed by Landlord, Landlord's predecessor-in-interest and/or
Landlord's assignee for the Project) may add thereto from time to time within or
as part of the Project; and (vi) the land upon which any of the foregoing are
situated.  The site plan depicting the current configuration of the Project is
attached hereto as Exhibit A-3.  Notwithstanding the foregoing or anything
contained in this Lease to the contrary, (A) Landlord has no obligation to
expand or otherwise make any improvements within the Project, including, without
limitation, any of the outside plaza areas, walkways, driveways, courtyards,
public and private streets, transportation facilitation areas and other
improvements and facilities which may be depicted on Exhibit A-3 attached hereto
(as the same may be modified by Landlord (and/or any other owners of Marina
Village) from time to time without notice to Tenant), other than (1) Landlord's
maintenance and repair obligations expressly set forth in this Lease, and (2)
Landlord's obligations (if any) specifically set forth in the Tenant Work Letter
attached hereto as Exhibit B, and (B) Landlord (and/or any other owners of
Marina Village) shall have the right from time to time to include or exclude any
improvements or facilities within the Project, at such party's sole election, as
more particularly set forth in Section 1.1.3 below (so long as such acts do not
materially, adversely affect Tenant's access to or use of the Premises for
Tenant's Permitted Use, as defined in Section 5.1 below).
 
1.1.3            Tenant's and Landlord's Rights.  Tenant shall have the right to
the nonexclusive use of the common corridors and hallways, stairwells, elevators
(if any), restrooms and other public or common areas located within the
Buildings, and the non-exclusive use of those areas located on the Project that
are designated by Landlord from time to time as common areas for the Buildings;
provided, however, that (i) Tenant's use thereof shall be subject to (A) the
provisions of any covenants, conditions and restrictions regarding the use
thereof now or hereafter recorded against the Project so long as such future
covenants, conditions and restrictions regarding the use thereof do not
materially, adversely affect Tenant's access to or use of the Premises for
Tenant's Permitted Use, and (B) such reasonable, non-discriminatory rules and
regulations as Landlord may make from time to time (which shall be provided in
writing to Tenant), and (ii) Tenant may not go on the roof of Buildings or the
Other Existing Buildings without Landlord's prior consent (which may be withheld
in Landlord's sole and absolute discretion) and without otherwise being
accompanied by a representative of Landlord.  Landlord (and/or any other owners
of Marina Village) reserve the right from time to time to use any of the common
areas of the Project, and the roof, risers and conduits of the Buildings and the
Other Existing Buildings for telecommunications and/or any other purposes, and
to do any of the following:  (1) make any changes, additions, improvements,
repairs and/or replacements in or to the Project or any portion or elements
thereof, including, without limitation, (x) changes in the location, size, shape
and number of driveways, entrances, loading and unloading areas, ingress,
egress, direction of traffic, landscaped areas, walkways, public and private
streets, plazas, courtyards, transportation facilitation areas and common areas,
and (y) expanding or decreasing the size of the Project and any common areas and
other elements thereof, including adding, deleting and/or excluding buildings
(including any of the Other Existing Buildings) thereon and therefrom; (2) close
temporarily any of the common areas while engaged in making repairs,
improvements or alterations to the Project; (3) retain and/or form a common area
association or associations under covenants, conditions and restrictions to own,
manage, operate, maintain, repair and/or replace all or any portion of the
landscaping, driveways, walkways, public and private streets, plazas,
courtyards, transportation facilitation areas and/or other common areas located
outside of the Buildings and the Other Existing Buildings and, subject to
Article 4 below, include the common area assessments, fees and taxes charged by
the association(s) and the cost of maintaining, managing, administering and
operating the association(s), in Operating Expenses or Tax Expenses; and (4)
perform such other acts and make such other changes with respect to the Project
as Landlord may, in the exercise of good faith business judgment, deem to be
appropriate (so long as such acts do not materially, adversely affect Tenant's
access to or use of the Premises for  Tenant's Permitted Use).

 
MARINA VILLAGE
[Biotime]

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

1.2           Condition of Premises.  Except as expressly set forth in this
Lease and in the Tenant Work Letter, Landlord shall not be obligated to provide
or pay for any improvement, remodeling or refurbishment work or services related
to the improvement, remodeling or refurbishment of the Premises, and Tenant
shall accept the Premises in its "As Is" condition on the date Landlord delivers
possession of the Premises to Tenant and on the Lease Commencement Date. 
Landlord shall deliver possession of the 1020 Premises and that portion of the
1010 Premises designated "Lab & Warehouse" on Exhibit A-4 attached hereto (the
"1010 Lab Space") to Tenant within one (1) business day after the mutual
execution and delivery of this Lease (and Tenant's delivery of all other items
required to be concurrently delivered to Landlord, e.g., Security Deposit,
evidence of insurance, etc.).  Landlord shall use commercially reasonable
efforts to deliver possession of that portion of the 1010 Premises designated
"Office Space" on Exhibit A-4 attached hereto (the "1010 Office Space") to
Tenant on or prior to February 1, 2016.  If Landlord does not deliver possession
of the 1010 Office Space to Tenant on or before February 1, 2016 (the "Outside
Delivery Date"), as such date shall be extended day for day for each day
Landlord is delayed in delivering possession of the 1010 Office Space to Tenant
as a result of events of Force Majeure (as defined in Section 24.17 below and
which for purposes of this Lease shall not include the failure or refusal of a
tenant to vacate or surrender possession of any portion of the 1010 Office
Space), then Landlord shall abate one (1) day of Base Rent otherwise payable for
the 1010 Office Space at the per diem rate of $.07 per rentable square foot of
the 1010 Office Space (collectively, the "Delay Abated Rent") for every one (1)
day of delay that Landlord fails to deliver possession of the 1010 Office Space
to Tenant beyond the Outside Delivery Date (as so extended); provided, however,
the Lease Expiration Date for the entire Premises shall be extended on a
day-for-day basis for each day that Tenant is entitled to Delay Abated Rent
pursuant to this Section 1.2.  The abatement right afforded to Tenant under this
Section 1.2 shall be Tenant's sole and exclusive remedy for Landlord's failure
to deliver possession of the 1010 Office Space to Tenant on or before the
Outside Delivery Date, as it may be extended as provided hereinabove.
 
1.3           Rentable Square Feet.  The rentable square feet of the Premises is
approximately as set forth in Section 6.1 of the Summary.  For purposes hereof,
the "rentable square feet" of the Premises and the Buildings shall be calculated
by Landlord pursuant to the Standard Method for Measuring Floor Area in Office
Buildings, ANSI Z65.1-2010 ("BOMA"), as modified for the Buildings pursuant to
Landlord's standard rentable area measurements for the Buildings, to include,
among other calculations, a portion of the common areas and service areas of the
Buildings.  The rentable square feet of the Premises and the Buildings are
subject to verification from time to time by Landlord's planner/designer and
such verification shall be made in accordance with the provisions of this
Section 1.3.  Tenant's architect may consult with Landlord's planner/designer
regarding such verification, except to the extent it relates to the rentable
square feet of the Buildings; provided, however, the determination of Landlord's
planner/designer shall be conclusive and binding upon the parties.  If
Landlord's planner/designer determines that the rentable square footage amounts
shall be different from those set forth in this Lease, all amounts, percentages
and figures appearing or referred to in this Lease based upon such incorrect
rentable square footage (including, without limitation, the amount of the Base
Rent and Tenant's Share) shall be modified in accordance with such
determination.  If such determination is made, it will be confirmed in writing
by Landlord to Tenant.
 
ARTICLE 2
 
LEASE TERM
 
The terms and provisions of this Lease shall be effective as of the date of this
Lease except for the provisions of this Lease relating to the payment of Rent. 
The term of this Lease (the "Lease Term") shall be as set forth in Section 7.1
of the Summary and shall commence on the date (the "Lease Commencement Date")
set forth in Section 7.2 of the Summary (subject, however, to the terms of the
Tenant Work Letter), and shall terminate on the date (the "Lease Expiration
Date") set forth in Section 7.3 of the Summary, unless this Lease is sooner
terminated as hereinafter provided.  For purposes of this Lease, the term "Lease
Year" shall mean each consecutive twelve (12) month period during the Lease
Term, provided that the last Lease Year shall end on the Lease Expiration Date. 
Following the Lease Commencement Date, Landlord shall deliver to Tenant an
amendment in the form as set forth in Exhibit C, attached hereto, setting forth,
among other things, the Lease Commencement Date and the Lease Expiration Date,
each as determined pursuant to Sections 7.2 and 7.3, respectively, of the
Summary, which amendment Tenant shall execute and return to Landlord within five
(5) business days after Tenant's receipt thereof.  If Tenant fails to execute
and return the amendment within such 5-business day period, Tenant shall be
deemed to have approved and confirmed the dates set forth therein, provided that
such deemed approval shall not relieve Tenant of its obligation to execute and
return the amendment (and such failure shall constitute a default by Tenant
hereunder).
 
ARTICLE 3
 
BASE RENT
 
Tenant shall pay, without notice or demand, to Landlord or Landlord's agent at
Landlord's address provided in Section 3 of the Summary, or at such other place
as Landlord may from time to time designate in writing, in currency or a check
for currency which, at the time of payment, is legal tender for private or
public debts in the United States of America, or at Landlord's election, by wire
or ACH transfer or as otherwise specified by Landlord, base rent ("Base Rent")
as set forth in Section 8 of the Summary, payable in equal monthly installments
as set forth in Section 8 of the Summary in advance on or before the first day
of each and every month during the Lease Term, without any setoff or deduction
whatsoever.  The Base Rent for the first full month of the Lease Term shall be
paid at the time of Tenant's execution of this Lease.  If any rental payment
date (including the Lease Commencement Date) falls on a day of the month other
than the first day of such month or if any rental payment is for a period which
is shorter than one month, then the rental for any such fractional month shall
be a proportionate amount of a full calendar month's rental based on the
proportion that the number of days in such fractional month bears to the number
of days in the calendar month during which such fractional month occurs.  All
other payments or adjustments required to be made under the terms of this Lease
that require proration on a time basis shall be prorated on the same basis.

 

 -2-
MARINA VILLAGE
[Biotime]

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

ARTICLE 4
 
ADDITIONAL RENT
 
4.1           Additional Rent.  In addition to paying the Base Rent specified in
Article 3 above, Tenant shall pay as additional rent the sum of the following:
(i) the applicable Tenant's Share (as defined below) of the annual Operating
Expenses allocated to the applicable Building as to which such Tenant's Share
pertains (pursuant to Section 4.3.4 below) which are in excess of the amount of
Operating Expenses allocated to such applicable Building and applicable to the
Expense Base Year; plus (ii) the applicable Tenant's Share of the annual Tax
Expenses allocated to the applicable Building as to which such Tenant's Share
pertains (pursuant to Section 4.3.4 below) which are in excess of the amount of
Tax Expenses allocated to such applicable Building and applicable to the Tax
Expense Base Year; plus (iii) the applicable Tenant's Share of the annual
Utilities Costs allocated to the applicable Building as to which such Tenant's
Share pertains (pursuant to Section 4.3.4 below) which are in excess of the
amount of Utilities Costs allocated to such applicable Building and applicable
to the Utilities Base Year.  Such additional rent, together with any and all
other amounts payable by Tenant to Landlord pursuant to the terms of this Lease
(including, without limitation, pursuant to Article 6), shall be hereinafter
collectively referred to as the "Additional Rent."  The Base Rent and Additional
Rent are herein collectively referred to as the "Rent."  All amounts due under
this Article 4 as Additional Rent shall be payable for the same periods and in
the same manner, time and place as the Base Rent.  Without limitation on other
obligations of Tenant which shall survive the expiration of the Lease Term, the
obligations of Tenant to pay the Additional Rent provided for in this Article 4
accruing during the Lease Term shall survive the expiration of the Lease Term.
 
4.2           Definitions.  As used in this Article 4, the following terms shall
have the meanings hereinafter set forth:
 
4.2.1            "Calendar Year" shall mean each calendar year in which any
portion of the Lease Term falls, through and including the calendar year in
which the Lease Term expires.
 
4.2.2            "Expense Base Year" shall mean the year set forth in Section
9.1 of the Summary.
 
4.2.3            "Expense Year" shall mean each Calendar Year.
 
4.2.4        "Operating Expenses" shall mean all expenses, costs and amounts of
every kind and nature which Landlord shall pay during any Expense Year because
of or in connection with the ownership, management, maintenance, repair,
restoration or operation of the Project, including, without limitation, any
amounts paid for:  (i) the cost of operating, maintaining, repairing, renovating
and managing the utility systems, mechanical systems, sanitary and storm
drainage systems, any elevator systems (if applicable) and all other Systems and
Equipment (as defined below), except as otherwise provided in this Lease, and
the cost of supplies and equipment and maintenance and service contracts in
connection therewith; (ii) the cost of licenses, certificates, permits and
inspections, and the cost of contesting the validity or applicability of any
governmental enactments which may affect Operating Expenses, and the costs
incurred in connection with implementation and operation (by Landlord or any
common area association(s) formed for the Project) of any transportation system
management program or similar program; (iii) the cost of insurance carried by
Landlord, in such amounts as Landlord may reasonably determine or as may be
required by any mortgagees of any mortgage or the lessor of any ground lease
affecting the Project; (iv) the cost of landscaping, relamping, supplies, tools,
equipment and materials, and all fees, charges and other costs (including
consulting fees, legal fees and accounting fees) incurred in connection with the
management, operation, repair and maintenance of the Project, including the fair
rental value of any on-site management office space (not exceeding 2,500
rentable square feet) provided for the management of the Project; provided,
however, any such management fees shall not exceed three percent (3%) of the
gross revenues of the Project; (v) any equipment rental agreements or management
agreements (including the cost of any management fee and the fair rental value
of any office space provided thereunder); (vi) wages, salaries and other
compensation and benefits of all persons engaged in the operation, management,
maintenance or security of the Project, and employer's Social Security taxes,
unemployment taxes or insurance, and any other taxes which may be levied on such
wages, salaries, compensation and benefits; (vii) payments under any easement,
license, operating agreement, declaration, restrictive covenant, underlying or
ground lease (excluding rent), or instrument pertaining to the sharing of costs
by the Project; (viii) the cost of janitorial service, trash removal (provided,
however, Operating Expenses shall not include the cost of janitorial services
and trash removal services provided to the Premises or the premises of other
tenants of the Buildings and/or the Project or the cost of replacing light
bulbs, lamps, starters and ballasts for lighting fixtures in the Premises and
the premises of other tenants in the Buildings and/or the Project to the extent
such services are directly provided and paid for by Tenant with respect to the
Premises pursuant to Section 6.5 below), alarm and security service, if any,
window cleaning, replacement of wall and floor coverings, ceiling tiles and
fixtures in lobbies, corridors, restrooms and other common or public areas or
facilities, maintenance and replacement of curbs and walkways, repair to roofs
and re-roofing; (ix) amortization (including interest on the unamortized cost)
of the cost of acquiring or the rental expense of personal property used in the
maintenance, operation and repair of the Project (x) the cost of any capital
improvements or other costs (I) which are intended as a labor-saving device or
to effect other economies in the operation or maintenance of the Project, (II)
made to the Project or any portion thereof after the Lease Commencement Date
that are required under any governmental law or regulation, or (III) which are
Conservation Costs (as defined below) and/or which are reasonably determined by
Landlord to be in the best interests of the Project; provided, however, that if
any such cost described in (I), (II) or (III) above, is a capital expenditure,
such cost shall be amortized (including interest on the unamortized cost) as
Landlord shall reasonably determine; and (xi) the costs and expenses of
complying with, or participating in, conservation, recycling, sustainability,
energy efficiency, waste reduction or other programs or practices implemented or
enacted from time to time at the Buildings and/or Project, including, without
limitation, in connection with any LEED (Leadership in Energy and Environmental
Design) rating or compliance system or program, including that currently
coordinated through the U.S. Green Building Council or Energy Star rating and/or
compliance system or program (collectively, "Conservation Costs").  If Landlord
is not furnishing any particular work or service (the cost of which, if
performed by Landlord, would be included in Operating Expenses) to a tenant who
has undertaken to perform such work or service in lieu of the performance
thereof by Landlord, Operating Expenses shall be deemed to be increased by an
amount equal to the additional Operating Expenses which would reasonably have
been incurred during such period by Landlord if it had at its own expense
furnished such work or service to such tenant.  Landlord shall not (A) make a
profit by charging items to Operating Expenses that are otherwise also charged
separately to others, and (B) collect Operating Expenses from Tenant and all
other tenants/occupants in the Building in an amount in excess of what Landlord
incurred for the items included in Operating Expenses.  If any of (x) the
Buildings, (y) the Other Existing Buildings (but only during the period of time
the same are included by Landlord within the Project) and (z) any additional
buildings are added to the Project pursuant to Section 1.1.3 above (but only
during the period of time after such additional buildings have been fully
constructed and ready for occupancy and are included by Landlord within the
Project) are less than ninety-five percent (95%) occupied during all or a
portion of any Expense Year (including the Expense Base Year), Landlord shall
make an appropriate adjustment to the variable components of Operating Expenses
for such year or applicable portion thereof, employing sound accounting and
management principles, to determine the amount of Operating Expenses that would
have been paid had the Buildings, such Other Existing Buildings and such
additional buildings (if any) been ninety-five percent (95%) occupied; and the
amount so determined shall be deemed to have been the amount of Operating
Expenses for such year, or applicable portion thereof.
 

 -3-
MARINA VILLAGE
[Biotime]

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

Subject to the provisions of Section 4.3.4 below, Landlord shall have the right,
from time to time, to reasonably and equitably allocate some or all of the
Operating Expenses (and/or Tax Expenses and Utilities Costs) between and/or
among different tenants of the Project, and/or among different buildings of the
Project as and when such different buildings are constructed and added to
(and/or excluded from) the Project or otherwise (the "Cost Pools"); provided,
however, all such allocations shall be consistently applied and implemented in a
non-discriminatory manner against Tenant.  Such Cost Pools may include, without
limitation, the office space tenants and the tech/R&D space tenants of the
Project (to the extent such Operating Expenses are reasonably and equitably
allocable to such tenants based upon use and/or other factors attributable to
such specific tenants) or of a building or buildings within the Project.  Such
Cost Pools may also include an allocation of certain Operating Expenses (and/or
Tax Expenses and Utilities Costs) within or under covenants, conditions and
restrictions affecting the Project.  In addition, Landlord shall have the right
from time to time, in its reasonable discretion, to include or exclude existing
or future buildings in the Project for purposes of determining Operating
Expenses, Tax Expenses and Utilities Costs and/or the provision of various
services and amenities thereto, including allocation of Operating Expenses, Tax
Expenses and Utilities Costs in any such Cost Pools.  In all events, if Landlord
elects to use Cost Pools or to modify Cost Pools after the applicable Expense
Base Year, Tax Expense Base Year or Utilities Base Year, or to include or
exclude existing buildings in the Project in its determination of Operating
Expenses, Tax Expenses and/or Utilities Costs (as the case may be), Landlord
shall make a corresponding adjustment to the Operating Expenses for the Expense
Base Year, Tax Expenses for the Tax Expense Base Year and Utilities Cost for the
Utilities Base Year, respectively (grossed up as appropriate), to reflect such
modifications, in order to insure that any such determination of Operating
Expenses, Tax Expenses and Utilities Costs  payable by Tenant shall be on an
"apples to apples" basis and shall not result in an unfair increase in the
Tenant's Share of increases in Operating Expenses, Tax Expenses and Utilities
Costs payable by Tenant hereunder.
 
Notwithstanding anything to the contrary set forth in this Article 4, when
calculating Operating Expenses for the Expense Base Year, Operating Expenses
shall exclude one-time Conservation Costs and other special charges, costs or
fees incurred in the Base Year only, including those attributable to market-wide
labor-rate increases or other extraordinary circumstances, including, but not
limited to, boycotts and strikes, and costs relating to capital improvements or
expenditures.
 
Notwithstanding the foregoing, Operating Expenses shall not, however, include:
(A) costs of leasing commissions, attorneys' fees and other costs and expenses
incurred in connection with negotiations or disputes with present or prospective
tenants or other occupants of the Project; (B) costs (including permit, license
and inspection costs) incurred in renovating or otherwise improving, decorating
or redecorating rentable space for other tenants or vacant rentable space; (C)
costs incurred due to the violation by Landlord of the terms and conditions of
any lease of space in the Project; (D) costs of overhead or profit increment
paid to Landlord or to subsidiaries or affiliates of Landlord for services in or
in connection with the Project to the extent the same exceeds the costs of
overhead and profit increment included in the costs of such services which could
be obtained from third parties on a competitive basis; (E) except as otherwise
specifically provided in this Section 4.2.4, costs of interest on debt or
amortization on any mortgages, and rent payable under any ground lease of the
Project; (F) Utilities Costs; (G) Tax Expenses; (H) the cost of providing any
service directly to and paid directly by any tenant; (I) advertising and
promotional expenditures; (J) marketing costs including any
sale/transfer/leasing commissions, attorneys' fees in connection with the
negotiation and preparation of letters, deal memos, letters of intent,
agreements, leases, subleases and/or assignments, space planning costs, and
other costs and expenses (other than tax expenses) incurred in connection with
sale/transfer/lease, sublease and/or assignment negotiations and transactions
with present or prospective purchasers, tenants or other occupants of the
Buildings or the Other Existing Buildings; (K) expenses in connection with
services or other benefits for which Tenant is charged directly but which are
provided to other tenants of the Buildings at no cost (or are separately
reimbursed by such other tenants); (L) costs incurred by Landlord for the repair
of damage to the Buildings or the Project, to the extent that Landlord is
reimbursed by insurance proceeds (or would have been reimbursed had Landlord
maintained the insurance required under Section 10.2 below); (M) costs incurred
to comply with Applicable Laws (as defined below) with respect to the cleanup,
removal, investigation and/or remediation (collectively, "Remediation Costs") of
any Hazardous Materials (as defined in Article 5 below) in, on or under the
Project and/or the Buildings to the extent such Hazardous Materials are:  (1) in
existence as of the Lease Commencement Date and in violation of Applicable Laws
in effect as of the Lease Commencement Date; or (2) introduced onto the Project
and/or the Buildings after the Lease Commencement Date by Landlord or any of
Landlord's agents, employees, contractors or other tenants in violation of
Applicable Laws in effect at the date of introduction; (N) costs arising from
Landlord's charitable or political contributions; (O) costs of acquisition of
sculptures, painting and other objects of art; (P) interest, penalties or other
costs arising out of Landlord's failure to make timely payment of any of its
obligations under this Lease, including, without limitation, Landlord's failure
to make timely payment of any item that is included in Operating Expenses, Tax
Expenses, or Utilities Costs; (Q) Landlord's general corporate overhead and
administrative expenses, except for the property management fee and except as
they relate to the specific management of the Project; (R) costs associated with
the operation of the business of the partnership or entity which constitutes
Landlord as the same are distinguished from the costs of operation of the
Buildings and/or the Project, including partnership accounting and legal
matters, costs of defending any lawsuits with or claims by any mortgagee (except
as the actions of Tenant may be in issue), costs of selling, syndicating,
financing, mortgaging or hypothecating any of Landlord's interest in the
Buildings or the Project, costs of any disputes between Landlord and its
employees (if any) not engaged in Buildings and/or Project operation, disputes
of Landlord with Project management, or outside fees paid in connection with
disputes with other tenants (except to the extent the expenditure of such
outside fees generally benefit all tenants of the Buildings or the Other
Existing Buildings and Landlord included such category of expenses or similar
types of expenses, if actually incurred, in the Expense Base Year); (S) costs
arising from the gross negligence or willful misconduct of Landlord and/or
Landlord's agents, employees and contractors; (T) costs of correcting defects in
the initial design or construction of the Buildings or Project; and (U) interest
on and capital retirement of Landlord's mortgage loans.
 

 -4-
MARINA VILLAGE
[Biotime]

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

4.2.5            "Systems and Equipment" shall mean any plant, machinery,
transformers, duct work, cable, wires, and other equipment, facilities, and
systems designed to supply heat, ventilation, air conditioning and humidity or
any other services or utilities, or comprising or serving as any component or
portion of the electrical, gas, steam, plumbing, sprinkler, communications,
alarm, security, or fire/life safety systems or equipment, or any other
mechanical, electrical, electronic, computer or other systems or equipment which
serve the Buildings and/or any common area in the Project in whole or in part.
 
4.2.6            "Tax Expense Base Year" shall mean the year set forth in
Section 9.2 of the Summary.
 
4.2.7            "Tax Expenses" shall mean all federal, state, county, or local
governmental or municipal taxes, fees, assessments, charges or other impositions
of every kind and nature, whether general, special, ordinary or extraordinary,
(including, without limitation, real estate taxes, general and special
assessments, transit assessments, fees and taxes, child care subsidies, fees
and/or assessments, job training subsidies, fees and/or assessments, open space
fees and/or assessments, housing subsidies and/or housing fund fees or
assessments, public art fees and/or assessments, leasehold taxes or taxes based
upon the receipt of rent, including gross receipts or sales taxes applicable to
the receipt of rent, personal property taxes imposed upon the fixtures,
machinery, equipment, apparatus, systems and equipment, appurtenances, furniture
and other personal property used in connection with the Project), which Landlord
shall pay during any Expense Year because of or in connection with the
ownership, leasing and operation of the Project or Landlord's interest therein. 
For purposes of this Lease, Tax Expenses shall be calculated as if (i) the
tenant improvements in the Buildings, the Other Existing Buildings and any
additional buildings added to the Project pursuant to Section 1.1.3 above (but
only during the period of time that such Other Existing Buildings and additional
buildings are included by Landlord within the Project) were fully constructed,
and (ii) the Project, the Buildings, such Other Existing Buildings and such
additional buildings (if any) and all tenant improvements therein were fully
assessed for real estate tax purposes.
 
4.2.7.1       Tax Expenses shall include, without limitation:
 
(i)           Any tax on Landlord's rent, right to rent or other income from the
Project or as against Landlord's business of leasing any of the Project;
 
(ii)          Any assessment, tax, fee, levy or charge in addition to, or in
substitution, partially or totally, of any assessment, tax, fee, levy or charge
previously included within the definition of real property tax, it being
acknowledged by Tenant and Landlord that Proposition 13 was adopted by the
voters of the State of California in the June 1978 election ("Proposition 13")
and that assessments, taxes, fees, levies and charges may be imposed by
governmental agencies for such services as fire protection, street, sidewalk and
road maintenance, refuse removal and for other governmental services formerly
provided without charge to property owners or occupants.  It is the intention of
Tenant and Landlord that all such new and increased assessments, taxes, fees,
levies, and charges and all similar assessments, taxes, fees, levies and charges
be included within the definition of Tax Expenses for purposes of this Lease;
 
(iii)        Any assessment, tax, fee, levy, or charge allocable to or measured
by the area of the Premises or the rent payable hereunder, including, without
limitation, any gross income tax upon or with respect to the possession,
leasing, operating, management, maintenance, alteration, repair, use or
occupancy by Tenant of the Premises, or any portion thereof;
 
(iv)        Any assessment, tax, fee, levy or charge, upon this transaction or
any document to which Tenant is a party, creating or transferring an interest or
an estate in the Premises; and
 
(v)         Any reasonable expenses incurred by Landlord in attempting to
protest, reduce or minimize Tax Expenses.
 

 -5-
MARINA VILLAGE
[Biotime]

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

4.2.7.2       In no event shall Tax Expenses for any Expense Year be less than
the Tax Expenses for the Tax Expense Base Year.
 
4.2.7.3       Notwithstanding anything to the contrary contained in this Section
4.2.7, there shall be excluded from Tax Expenses (i) all excess profits taxes,
franchise taxes, gift taxes, capital stock taxes, inheritance and succession
taxes, estate taxes, federal and state net income taxes, and other taxes to the
extent applicable to Landlord's net income (as opposed to rents, receipts or
income attributable to operations at the Project), (ii) any items included as
Operating Expenses, and (iii) any items paid by Tenant under Section 4.4 below.
 
4.2.8            "Tenant's 1010 Share" shall mean the percentage set forth in
Section 9.4 of the Summary.  Tenant's 1010 Share was calculated by dividing the
number of rentable square feet of the 1010 Premises by the total rentable square
feet in the 1010 Building (as set forth in Section 9.4 of the Summary), and
stating such amount as a percentage.  "Tenant's 1020 Share" shall mean the
percentage set forth in Section 9.5 of the Summary.  Tenant's 1020 Share was
calculated by dividing the number of rentable square feet of the 1020 Premises
by the total rentable square feet in the 1020 Building (as set forth in Section
9.5 of the Summary), and stating such amount as a percentage.  Each of Tenant's
1010 Share and Tenant's 1020 Share may be referred to in this Lease as "Tenant's
Share".  Landlord shall have the right from time to time to redetermine the
rentable square feet of the 1010 Premises, the 1020 Premises and/or the
Buildings, and the applicable Tenant's Share shall be appropriately adjusted to
reflect any such redetermination.  If any applicable Tenant's Share is adjusted
pursuant to the foregoing, as to the Expense Year in which such adjustment
occurs, such applicable Tenant's Share for such year shall be determined on the
basis of the number of days during such Expense Year that each such applicable
Tenant's Share was in effect.
 
4.2.9            "Utilities Base Year" shall mean the year set forth in Section
9.3 of the Summary.
 
4.2.10         "Utilities Costs" shall mean all actual charges for utilities for
the Buildings and the Project (including utilities for the Other Existing
Buildings and additional buildings, if any, added to the Project during the
period of time the same are included by Landlord within the Project) which
Landlord shall pay during any Expense Year, including, but not limited to, the
costs of water, sewer, gas and electricity, and the costs of HVAC (as defined
below) and other utilities, as well as related fees, assessments, measurement
meters and devices and surcharges; provided, however, Utilities Costs shall not
include the costs of those utilities provided to the Premises and the premises
of other tenants of the Project since Tenant is responsible for providing and
paying for all utilities to the Premises pursuant to Section 6.1 below. 
Utilities Costs shall be calculated assuming the Buildings (and, during the
period of time when such buildings are included by Landlord within the Project,
the Other Existing Buildings and any additional buildings, if any, added to the
Project) are at least ninety-five percent (95%) occupied.  Except as otherwise
provided in this Section 4.2.10, Utilities Costs shall include any costs of
utilities which are allocated to the Project under any declaration, restrictive
covenant, or other instrument pertaining to the sharing of costs by the Project
or any portion thereof, including any covenants, conditions or restrictions now
or hereafter recorded against or affecting the Project.  For purposes of
determining Utilities Costs incurred for the Utilities Base Year, Utilities
Costs for the Utilities Base Year shall not include any one-time Conservation
Costs or other special charges, costs or fees or extraordinary charges or costs
incurred in the Utilities Base Year only, including those attributable to
boycotts, embargoes, strikes or other shortages of services or fuel.
 
4.3           Calculation and Payment of Additional Rent.
 
4.3.1            Calculation of Excess.  If for any Expense Year ending or
commencing within the Lease Term, (i) the applicable Tenant's Share of Operating
Expenses allocated to the applicable Building as to which such Tenant's Share
pertains pursuant to Section 4.3.4 below for such Expense Year exceeds such
applicable Tenant's Share of Operating Expenses allocated to such Building for
the Expense Base Year, and/or (ii) the applicable Tenant's Share of Tax Expenses
allocated to the applicable Building as to which Tenant's Share pertains
pursuant to Section 4.3.4 below for such Expense Year exceeds such applicable
Tenant's Share of Tax Expenses allocated to such Building for the Tax Expense
Base Year, and/or (iii) the applicable Tenant's Share of Utilities Costs
allocated to the applicable Building as to which Tenant's Share pertains
pursuant to Section 4.3.4 below for such Expense Year exceeds such applicable
Tenant's Share of Utilities Costs allocated to such Building for the Utilities
Base Year, then Tenant shall pay to Landlord, in the manner set forth in Section
4.3.2, below, and as Additional Rent, an amount equal to such excess (the
"Excess").
 
4.3.2            Statement of Actual Operating Expenses, Tax Expenses and
Utilities Costs and Payment by Tenant.  Landlord shall endeavor to give to
Tenant on or before the first (1st) day of June following the end of each
Expense Year, a statement (the "Statement") which shall state the Operating
Expenses, Tax Expenses and Utilities Costs incurred or accrued for such
preceding Expense Year, and which shall indicate the amount, if any, of any
Excess.  Within thirty (30) days after Tenant's receipt of the Statement for
each Expense Year ending during the Lease Term, Tenant shall pay to Landlord the
full amount of the Excess for such Expense Year, less the amounts, if any, paid
during such Expense Year as Estimated Excess (as defined in and pursuant to
Section 4.3.3 below).  If any Statement reflects that the amount of Estimated
Excess paid by Tenant to Landlord for such Expense Year is greater than the
actual amount of the Excess for such Expense Year, then Landlord shall, at
Landlord's option, either (i) remit such overpayment to Tenant within thirty
(30) days after such applicable Statement is delivered to Tenant, or (ii) credit
such overpayment toward the additional Rent next due and payable to Tenant under
this Lease.  The failure of Landlord to timely furnish the Statement for any
Expense Year shall not prejudice Landlord from enforcing its rights under this
Article 4.  If the Statement for the Expense Year in which this Lease terminates
reflects that Tenant's payment to Landlord of Estimated Excess for such Expense
Year was greater than or less than the actual amount of Excess for such last
Expense Year, then within thirty (30) days after Landlord's delivery of such
Statement to Tenant, Landlord shall refund to Tenant any such overpayment or
Tenant shall pay to Landlord any such underpayment, as the case may be.  The
provisions of this Section 4.3.2 shall survive the expiration or earlier
termination of the Lease Term.
 

 -6-
MARINA VILLAGE
[Biotime]

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

4.3.3            Statement of Estimated Operating Expenses, Tax Expenses and
Utilities Costs.  In addition, Landlord shall endeavor to give Tenant a yearly
expense estimate statement (the "Estimate Statement") which shall set forth
Landlord's reasonable estimate (the "Estimate") of what the total amount of
Operating Expenses, Tax Expenses and Utilities Costs allocated to the Buildings
pursuant to Section 4.3.4 below for the then-current Expense Year shall be and
the estimated Excess (the "Estimated Excess") as calculated by comparing (i) the
applicable Tenant's Share of Operating Expenses allocated to the applicable
Building as to which such Tenant's Share pertains, which shall be based upon the
Estimate, to such applicable Tenant's Share of Operating Expenses allocated to
such Building for the Expense Base Year, (ii) the applicable Tenant's Share of
Tax Expenses allocated to the applicable Building as to which such Tenant's
Share pertains, which shall be based upon the Estimate, to such applicable
Tenant's Share of Tax Expenses allocated to such Building for the Tax Expense
Base Year, and (iii) the applicable Tenant's Share of Utilities Costs allocated
to the applicable Building as to which such Tenant's Share pertains, which shall
be based upon the Estimate, to such applicable Tenant's Share of Utilities Costs
allocated to such Building for the Utilities Base Year.  The failure of Landlord
to timely furnish the Estimate Statement for any Expense Year shall not preclude
Landlord from enforcing its rights to collect any Estimated Excess under this
Article 4.  If pursuant to the Estimate Statement an Estimated Excess is
calculated for the then-current Expense Year, Tenant shall pay, with its next
installment of Base Rent due, a fraction of the Estimated Excess for the
then-current Expense Year (reduced by any amounts paid pursuant to the last
sentence of this Section 4.3.3).  Such fraction shall have as its numerator the
number of months which have elapsed in such current Expense Year to the month of
such payment, both months inclusive, and shall have twelve (12) as its
denominator.  Until a new Estimate Statement is furnished, Tenant shall pay
monthly, with the monthly Base Rent installments, an amount equal to one-twelfth
(1/12) of the total Estimated Excess set forth in the previous Estimate
Statement delivered by Landlord to Tenant.
 
4.3.4            Allocation of Operating Expenses, Tax Expenses and Utilities
Costs to Buildings.  The parties acknowledge that the Buildings are part of a
multi-building commercial project consisting of the Buildings, and the Other
Existing Buildings and such other buildings as Landlord (and/or any other owners
of Marina Village) may elect to construct and include as part of the Project
from time to time (the Other Existing Buildings and any such other buildings are
sometimes referred to herein, collectively, as the "Other Buildings"), and that
certain of the costs and expenses incurred in connection with the Project (i.e.
the Operating Expenses, Tax Expenses and Utilities Costs) shall be shared
between and/or among the Buildings and/or such Other Buildings, while certain
other costs and expenses which are solely attributable to the Buildings and such
Other Buildings, as applicable, shall be allocated directly to those
Buildings and the Other Buildings, respectively, as to which such costs and
expenses are solely attributable.  Accordingly, as set forth in Sections 4.1 and
4.2 above, Operating Expenses, Tax Expenses and Utilities Costs are determined
annually for the Project as a whole, and a portion of the Operating Expenses,
Tax Expenses and Utilities Costs, which portion shall be determined by Landlord
on an equitable basis, shall be allocated to each applicable Building (as
opposed to the other Building and the Other Buildings), and such portion so
allocated shall be the amount of Operating Expenses, Tax Expenses and Utilities
Costs payable with respect to such Building upon which the applicable Tenant's
Share shall be calculated.  Such portion of the Operating Expenses, Tax Expenses
and Utilities Costs allocated to each applicable Building shall include all
Operating Expenses, Tax Expenses and Utilities Costs which are attributable
solely to such Building, and an equitable portion of the Operating Expenses, Tax
Expenses and Utilities Costs attributable to the Project as a whole.  As an
example of such allocation with respect to Tax Expenses and Utilities Costs, it
is anticipated that Landlord (and/or any other owners of Marina Village) may
receive separate tax bills which separately assess the improvements component of
Tax Expenses for each building in the Project and/or Landlord may receive
separate utilities bills from the utilities companies identifying the Utilities
Costs for certain of the utilities costs directly incurred by each such building
(as measured by separate meters installed for each such building), and such
separately assessed Tax Expenses and separately metered Utilities Costs shall be
calculated for and allocated separately to each such applicable building.  In
addition, if Landlord (and/or any other owners of Marina Village) elect to
subdivide certain common area portions of the Project such as landscaping,
public and private streets, driveways, walkways, courtyards, plazas,
transportation facilitation areas and/or accessways into a separate parcel or
parcels of land (and/or separately convey all or any of such parcels to a common
area association to own, operate and/or maintain same), the Operating Expenses,
Tax Expenses and Utilities Costs for such common area parcels of land may be
aggregated and then reasonably allocated by Landlord to the 1010 Building, the
1020 Building and such Other Buildings on an equitable basis as Landlord (and/or
any applicable covenants, conditions and restrictions for any such common area
association) shall provide from time to time.
 
4.4           Taxes and Other Charges for Which Tenant Is Directly Responsible. 
Tenant shall reimburse Landlord upon demand for all taxes or assessments
required to be paid by Landlord (except to the extent included in Tax Expenses
by Landlord), excluding state, local and federal personal or corporate income
taxes measured by the net income of Landlord from all sources and estate and
inheritance taxes, whether or not now customary or within the contemplation of
the parties hereto, when:
 
4.4.1            said taxes are measured by or reasonably attributable to the
cost or value of Tenant's equipment, furniture, fixtures and other personal
property located in the Premises, or by the cost or value of any leasehold
improvements made in or to the Premises by or for Tenant, to the extent the cost
or value of such leasehold improvements exceeds the cost or value of a building
standard build-out as determined by Landlord regardless of whether title to such
improvements shall be vested in Tenant or Landlord;
 
4.4.2            said taxes are assessed upon or with respect to the possession,
leasing, operation, management, maintenance, alteration, repair, use or
occupancy by Tenant of the Premises or any portion of the Project; or
 
4.4.3            said taxes are assessed upon this transaction or any document
to which Tenant is a party creating or transferring an interest or an estate in
the Premises.
 

 -7-
MARINA VILLAGE
[Biotime]

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

4.5           Late Charges.  If any installment of Rent or any other sum due
from Tenant shall not be received by Landlord or Landlord's designee by the due
date therefor, then Tenant shall pay to Landlord a late charge equal to five
percent (5%) of the amount due plus any attorneys' fees incurred by Landlord by
reason of Tenant's failure to pay Rent and/or other charges when due hereunder. 
The late charge shall be deemed Additional Rent and the right to require it
shall be in addition to all of Landlord's other rights and remedies hereunder,
at law and/or in equity and shall not be construed as liquidated damages or as
limiting Landlord's remedies in any manner.  In addition to the late charge
described above, any Rent or other amounts owing hereunder which are not paid by
the date that they are due shall thereafter bear interest until paid at a rate
(the "Interest Rate") equal to the lesser of (i) the "Prime Rate" or "Reference
Rate" announced from time to time by the Bank of America (or such reasonable
comparable national banking institution as selected by Landlord if Bank of
America ceases to exist or publish a Prime Rate or Reference Rate), plus four
percent (4%), or (ii) the highest rate permitted by Applicable Law.
 
4.6           Audit Rights.  If Tenant disputes the amount of the Operating
Expenses, Tax Expenses and Utilities Costs set forth in the Statement for the
particular Expense Year delivered by Landlord to Tenant pursuant to Section
4.3.2 above, Tenant shall have the right, at Tenant's cost, upon thirty (30)
days' prior written notice to Landlord, to have Tenant's authorized employees
inspect, at Landlord's offices during normal business hours, Landlord's books,
records and supporting documents concerning the Operating Expenses, Tax Expenses
and Utilities Costs set forth in such Statement; provided, however, Tenant shall
have no right to conduct such inspection, have an audit performed by the
Accountant (as defined and described hereinbelow), or object to or otherwise
dispute the amount of the Operating Expenses, Tax Expenses and Utilities Costs
set forth in any such Statement unless Tenant notifies Landlord of such
objection and dispute, completes such inspection, and has the Accountant
commence and complete such audit within the one (1) year immediately following
Landlord's delivery of the particular Statement in question (the "Review
Period"); provided, further, that notwithstanding any such timely objection,
dispute, inspection, and/or audit, and as a condition precedent to Tenant's
exercise of its right of objection, dispute, inspection and/or audit as set
forth in this Section 4.6, Tenant shall not be permitted to withhold payment of,
and Tenant shall timely pay to Landlord, the full amounts as required by the
provisions of this Article 4 in accordance with such Statement.  However, such
payment may be made under protest pending the outcome of any audit which may be
performed by the Accountant as described below.  In connection with any such
inspection by Tenant, Landlord and Tenant shall reasonably cooperate with each
other so that such inspection can be performed pursuant to a mutually acceptable
schedule, in an expeditious manner and without undue interference with
Landlord's operation and management of the Project.  If after such inspection
and/or request for documentation, Tenant still disputes the amount of the
Operating Expenses, Tax Expenses and Utilities Costs set forth in the Statement,
Tenant shall have the right, within the Review Period, to cause a nationally
and/or regionally recognized independent certified public accountant (which is
not paid on a commission or contingency basis and which has not been engaged by
Tenant within the preceding five (5) year period) mutually approved by Landlord
and Tenant, which approval shall not be unreasonably withheld or delayed (the
"Accountant") to complete an audit of Landlord's books and records to determine
the proper amount of the Operating Expenses, Tax Expenses and Utilities Costs
incurred and amounts payable by Tenant for the Expense Year which is the subject
of such Statement.  Such audit by the Accountant shall be final and binding upon
Landlord and Tenant.  If Landlord and Tenant cannot mutually agree as to the
identity of the Accountant within thirty (30) days after Tenant notifies
Landlord that Tenant desires an audit to be performed, then the Accountant shall
be one of the following accounting firms (which is not paid on a commission or
contingency basis and which has not been engaged by Tenant within the preceding
five (5) year period), as selected by Tenant:  (i) OUM, (ii) Grant Thornton,
and/or (iii) Moss Adams LLP.  If such audit reveals that Landlord has
over-charged Tenant, then within thirty (30) days after the results of such
audit are made available to Landlord, Landlord shall reimburse to Tenant the
amount of such over-charge, together with interest on the amount of the
over-charge at the Interest Rate.  If the audit reveals that the Tenant was
under-charged, then within thirty (30) days after the results of such audit are
made available to Tenant, Tenant shall reimburse to Landlord the amount of such
under-charge.  Tenant agrees to pay the cost of such audit unless it is
subsequently determined that Landlord's original Statement which was the subject
of such audit overstated Operating Expenses, Tax Expenses and Utilities Costs by
five percent (5%) or more of the actual Operating Expenses, Tax Expenses and
Utilities Costs verified by such audit, in which case Landlord shall reimburse
Tenant for the reasonable cost of such audit (but not in excess of the amount of
the Operating Expenses, Tax Expenses and Utilities Costs so overstated).  The
payment by Tenant of any amounts pursuant to this Article 4 shall not preclude
Tenant from questioning, during the Review Period, the correctness of the
particular Statement in question provided by Landlord, but the failure of Tenant
to object thereto, conduct and complete its inspection and have the Accountant
conduct the audit as described above prior to the expiration of the Review
Period for such Statement shall be conclusively deemed Tenant's approval of the
Statement in question and the amount of Operating Expenses, Tax Expenses and
Utilities Costs shown thereon.  In connection with any inspection and/or audit
conducted by Tenant pursuant to this Section 4.6, Tenant agrees to keep, and to
cause all of Tenant's employees and consultants and the Accountant to keep, all
of Landlord's books and records and the audit, and all information pertaining
thereto and the results thereof, strictly confidential, and in connection
therewith, Tenant shall cause such employees, consultants and the Accountant to
execute such reasonable confidentiality agreements as Landlord may require prior
to conducting any such inspections and/or audits.
 

 -8-
MARINA VILLAGE
[Biotime]

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

ARTICLE 5
 
USE OF PREMISES
 
5.1       Use. Tenant shall use the Premises solely for general office and R&D
purposes, including research and development pertaining to stem cells, cancer
diagnostic testing from blood and urine samples, as well as the development and
light manufacturing of stem cell-based products and hydrogels to assist in
transplanting cells during surgical procedures and related uses, all consistent
with the character of the Buildings as first-class office and R&D buildings (the
"Permitted Use"), and Tenant shall not use or permit the Premises to be used for
any other purpose or purposes whatsoever. Tenant shall not use, or suffer or
permit any person or persons to use, the Premises or any part thereof for any
use or purpose contrary to the provisions of Exhibit D, attached hereto, or in
violation of the laws of the United States of America, the state in which the
Project is located, or the ordinances, regulations or requirements of the local
municipal or county governing body or other lawful authorities having
jurisdiction over the Project. Tenant shall comply with the Rules and
Regulations and all recorded covenants, conditions, and restrictions, and the
provisions of all ground or underlying leases, now or hereafter affecting the
Project (but with respect to any new or amended covenants, conditions,
restrictions, and ground or underlying leases, only after Tenant has received
thirty (30) days' prior written notice thereof from Landlord); provided,
however, that (i) in the event of conflict between the Rules and Regulations and
any modifications thereto and the terms of this Lease, this Lease shall control;
(ii) such Rules and Regulations are not enforced on a discriminatory basis
against Tenant; and (iii) in no event shall Landlord enter into any new
covenants, conditions or restrictions affecting the Project or consent to any
modification to any existing covenants, conditions, and restrictions affecting
the Project that would materially increase Tenant’s obligations under this Lease
or materially restrict or reduce Tenant’s rights under this Lease.
 
5.2           Hazardous Materials.  Tenant shall not use or allow another person
or entity to use any part of the Premises for the storage, use, treatment,
manufacture or sale of Hazardous Material. except that Tenant may use in the
Premises:  (i) general office supplies typically used in an office area in the
ordinary course of business, such as copier toner, liquid paper, glue, ink, and
cleaning solvents, but only to the extent the same are used by Tenant in the
manner for which they were designed and in compliance with all Applicable Laws
and the provisions of this Lease; and (ii) customary substances used in
connection with Tenant's Permitted Use (A) a list of which and the materials
safety data sheets for which shall be submitted to and must be pre-approved by
Landlord before use by Tenant, (B) which are used only in connection with and as
part of, and in such amounts as may be normal for, Tenant's Permitted Use
conducted by Tenant in the Premises, and (C) which are handled and disposed of
in a safe and healthful manner, in accordance with all applicable governmental
laws, rules and regulations, in accordance with any requirements, conditions,
rules and regulations that Landlord may impose in connection therewith, and in
accordance with the provision of this Section 5.2 and the other applicable
provisions of this Lease.  Tenant shall indemnify, defend, protect and hold
harmless the Landlord Parties (as defined below) from and against any and all
Claims (as defined below) incurred in connection with or arising from violation
of this Section 5.2 by Tenant, or any person claiming by, through or under
Tenant, or of the contractors, agents, employees, licensees or invitees of
Tenant.  As used herein, the term "Hazardous Material" means any hazardous or
toxic substance, material or waste which is or becomes regulated by any local
governmental authority, the state in which the Project is located or the United
States Government.
 
ARTICLE 6
 
SERVICES AND UTILITIES
 
6.1           Tenant's Responsibility.  Tenant shall be solely responsible, at
its sole cost and expense, for the furnishing of all utilities to the Premises
(except for the provision of water and sewer services as provided below in this
Section 6.1), including, but not limited to, HVAC, gas, electricity, telephone
and telecommunications (subject to Section 8.4 below).  In connection with the
foregoing, Tenant hereby agrees that:  (i) Landlord shall have absolutely no
obligation to provide any such utilities to the Premises, although Landlord
shall maintain and keep in service the existing utility connections located
outside the Buildings and connected to the exterior of the Buildings as
necessary for distribution of such utilities to the Premises by Tenant; (ii)
Tenant shall contract directly with the applicable utility providers to provide
all such utilities to the Premises, which utilities shall be separately metered,
at Tenant's cost; and (iii) Tenant shall pay for the costs of all such utilities
consumed at the Premises directly to the applicable provider thereof. 
Notwithstanding the foregoing, Landlord shall provide to the Premises city water
from the regular Building outlets for drinking, lavatory and toilet purposes and
sewer services, the costs of which shall be included in Utilities Costs.
 
6.2           Overstandard Tenant Use.  If Tenant shall use, or desire to use,
electricity, water, gas, sewer, HVAC or any other utilities for the Premises in
quantities that exceed the capacity of the equipment supplying the same to the
Buildings or that are in excess of the quantities normally required for ordinary
office use or R&D use for premises in the Comparable Buildings (as defined in
the Extension Option Rider), then, (i) subject to Applicable Laws, and subject
to Landlord's approval, which shall not be unreasonably withheld, conditioned or
delayed, Tenant shall, at Tenant's sole cost and expense, install such
supplemental equipment as may be reasonably required to provide such excess
capacity, and (ii) Tenant shall pay for the costs of any increased wear and tear
on existing Systems and Equipment caused by such excess use.
 
6.3           Interruption of Use.  Tenant agrees that subject to Section 6.6
below, Landlord shall not be liable for damages, by abatement of Rent or
otherwise, for failure to furnish or delay in furnishing any utilities or
services (including telephone and telecommunication services), or for any
diminution in the quality or quantity thereof, when such failure or delay or
diminution is occasioned, in whole or in part, by repairs, replacements, or
improvements, by any strike, labor lockout by third (3rd) party vendors or other
labor trouble, by inability to secure electricity, gas, water, or other fuel at
the Buildings or Project after reasonable effort to do so, by any accident or
casualty whatsoever, by act or default of Tenant or other parties, or by any
other cause; and such failures or delays or diminution shall never be deemed to
constitute an eviction or disturbance of Tenant's use and possession of the
Premises or relieve Tenant from paying Rent or performing any of its obligations
under this Lease.  Furthermore, Landlord shall not be liable under any
circumstances for a loss of, or injury to, property or for injury to, or
interference with, Tenant's business, including, without limitation, loss of
profits, however occurring, through or in connection with or incidental to a
failure to furnish any of the services or utilities as set forth in this Article
6.
 
6.4           Additional Services.  Landlord shall also have the exclusive
right, but not the obligation, to provide any additional services which may be
required by Tenant, including, without limitation, locksmithing  and additional
repairs and maintenance, provided that Tenant shall pay to Landlord within ten
(10) days after billing and as Additional Rent hereunder, the sum of all costs
to Landlord of such additional services plus a five percent (5%) administration
fee.
 

 -9-
MARINA VILLAGE
[Biotime]

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

6.5           Janitorial Service.  Landlord shall not be obligated to provide
any janitorial services to the Premises or replace any light bulbs, lamps,
starters and ballasts for lighting fixtures within the Premises.  Tenant shall
be solely responsible, at Tenant’s sole cost and expense, for (i) performing all
janitorial services, trash removal and other cleaning of the Premises, and (ii)
replacement of all light bulbs, lamps, starters and ballasts for lighting
fixtures within the Premises, all as appropriate to maintain the Premises in a
first-class manner consistent with the first-class nature of the Buildings and
Project.  Such services to be provided by Tenant shall be performed by
contractors and pursuant to service contracts reasonably approved by Landlord. 
Landlord shall have the right to inspect the Premises upon reasonable notice to
Tenant and to require Tenant to provide additional cleaning, if necessary.  If
Tenant shall fail to provide any of the services described in this Section 6.5
to be performed by Tenant within five (5) days after notice from Landlord, which
notice shall not be required in the event of an emergency, Landlord shall have
the right to provide such services and any charge or cost incurred by Landlord
in connection therewith shall be deemed Additional Rent due and payable by
Tenant upon receipt by Tenant of a written statement of cost from Landlord.
 
6.6           Abatement of Rent When Tenant Is Prevented From Using Premises. 
If Tenant is prevented from using, and does not use, the Premises or any portion
thereof, as a result of (i) Landlord's failure to maintain and keep in service
the existing utility connections located outside the Buildings and connected to
the exterior of the Buildings as necessary for distribution of such utilities to
the Premises required to be provided in Section 6.1 above, but only to the
extent such failure is caused by Landlord's negligence or willful misconduct,
(ii) any failure by Landlord to perform any repairs required to be performed by
Landlord under this Lease within fifteen (15) days after Landlord's receipt of
any such notice from Tenant (which 15-day period shall be extended as is
reasonably necessary if more than fifteen (15) days are reasonably required to
complete such repairs and Landlord commences such repairs within such 15-day
period and thereafter diligently attempts to complete same), (iii) the
performance of Landlord's Construction (as defined in Section 24.29 below), (iv)
any failure by Landlord to provide access to the Premises, or access to, or use
of, those parking spaces allocated to Tenant pursuant to Section 12 of the
Summary (to the extent replacement parking passes are not provided by Landlord),
or (v) Landlord's entry into the Premises pursuant to Article 22 below (each, an
"Abatement Event"), then Tenant shall give Landlord notice of such Abatement
Event.  If such Abatement Event continues for five (5) consecutive business days
after Landlord's receipt of any such notice from Tenant ("Eligibility Period"),
then Tenant's obligation to pay Base Rent and Tenant's Share of increases in
Operating Expenses, Tax Expenses and Utilities Costs shall be abated or reduced,
as the case may be, from and after the first (1st) day following the Eligibility
Period and continuing during such time that Tenant continues to be so prevented
from using, and does not use, the Premises or a portion thereof, in the
proportion that the rentable square feet of the portion of the Premises that
Tenant is prevented from using, and does not use, bears to the total rentable
square feet of the Premises.  To the extent Tenant shall be entitled to
abatement of Base Rent and Tenant's Share of increases in Operating Expenses,
Tax Expenses and Utilities Costs because of a damage or destruction pursuant to
Article 11 below, or a taking pursuant to Article 12 below, then the Eligibility
Period shall not be applicable.
 
6.7           Access to Premises.  Subject to the other provisions of this Lease
(including, without limitation, the Rules and Regulations attached to this Lease
as Exhibit D and any reasonable, non-discriminatory modifications thereof
adopted by Landlord from time to time), Tenant shall be granted access to the
Premises twenty-four (24) hours per day, seven (7) days per week, every day of
the year.

ARTICLE 7
 
REPAIRS
 
7.1           Tenant's Repairs.  Subject to Landlord's repair obligations in
Sections 7.2 and 11.1 below, Tenant shall, at Tenant's own expense, keep the
Premises, including all improvements, fixtures and furnishings therein, in good
order, repair and condition at all times during the Lease Term, which repair
obligations shall include, without limitation, the obligation to promptly and
adequately repair all damage to the Premises and replace or repair all damaged
or broken fixtures and appurtenances; provided however, that, at Landlord's
option, or if Tenant fails to make such repairs, Landlord may, but need not,
make such repairs and replacements, and Tenant shall pay Landlord the cost
thereof, including a percentage of the cost thereof (to be uniformly established
for the Buildings) sufficient to reimburse Landlord for all overhead, general
conditions, fees and other costs or expenses arising from Landlord's involvement
with such repairs and replacements forthwith upon being billed for same.
 
7.2           Landlord's Repairs.  Anything contained in Section 7.1 above to
the contrary notwithstanding, and subject to Articles 11 and 12 below, Landlord
shall repair and maintain (and replace if necessary, in Landlord's commercially
reasonable discretion) in good order, repair and condition:  (i) the structural
portions of the Buildings, including all foundations, walls, roofs, exterior
doors and windows; (ii) the basic plumbing, HVAC and electrical systems and all
other Systems and Equipment of the Buildings serving the Buildings and not
located in the Premises; and (iii) the common areas of the Buildings and
Project, including the common area restrooms of the Buildings (including all
plumbing and fixtures therein) and the common area hallways of the Buildings
(including the lighting fixtures and lightbulbs thereof); provided, however, to
the extent such maintenance and repairs are caused by the act, neglect, fault of
or omission of any duty by Tenant, its agents, servants, employees or invitees,
Tenant shall pay to Landlord as Additional Rent, the reasonable cost of such
maintenance and repairs.  Except as provided in Section 6.6 above, Landlord
shall not be liable for any failure to make any such repairs, or to perform any
maintenance, and there shall be no abatement of rent and no liability of
Landlord by reason of any injury to or interference with Tenant's business
arising from the making of any repairs, alterations or improvements in or to any
portion of the Project, Buildings or the Premises or in or to fixtures,
appurtenances and equipment therein.  Tenant hereby waives and releases its
right to make repairs at Landlord's expense under Sections 1941 and 1942 of the
California Civil Code; or under any similar law, statute, or ordinance now or
hereafter in effect.  Notwithstanding anything to the contrary contained in this
Lease, with respect to any replacement of the base building Systems and
Equipment which is required to be performed by Landlord during the period from
the Lease Commencement Date through and including the date that is one (1) year
after the Lease Commencement Date (the "Building Warranty Period"), subject to
the limitations set forth hereinbelow, Landlord shall be responsible for
performing such replacement, at Landlord's expense (which shall not be included
in Operating Expenses); provided, however, that to the extent such replacement
is caused by or is required as a result of (i) the act, neglect, fault of or
omission of any duty by Tenant, its agents, employees, contractors, licensees or
invitees, (ii) Tenant's use of electricity, water, HVAC or any other utilities
in the Premises (A) in quantities that exceed the capacity of the base building
Systems and Equipment, and/or (B) in excess of the quantities normally required
for ordinary office or R&D use for the Comparable Buildings, (iii) Tenant's
failure to perform Tenant's repair, maintenance and/or other obligations under
this Lease, and/or (iv) any Tenant Improvements or Alterations installed by or
on behalf of Tenant pursuant to the Tenant Work Letter and/or Article 8 below,
then Tenant shall reimburse Landlord for all such costs incurred by Landlord in
connection with such replacement within thirty (30) days after Tenant's receipt
of invoice therefor from Landlord.
 

 -10-
MARINA VILLAGE
[Biotime]

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

ARTICLE 8
 
ADDITIONS AND ALTERATIONS
 
8.1           Landlord's Consent to Alterations.  Tenant may not make any
improvements, alterations, additions or changes to the Premises (collectively,
the "Alterations") without first procuring the prior written consent of Landlord
to such Alterations, which consent shall be requested by Tenant not less than
thirty (30) days prior to the commencement thereof, and which consent shall not
be unreasonably withheld by Landlord; provided, however, Landlord may withhold
its consent in its sole and absolute discretion with respect to any Alterations
which may affect the structural components of the Buildings or the Systems and
Equipment or which can be seen from outside the Premises.  Tenant shall pay for
all overhead, general conditions, fees and other costs and expenses of the
Alterations, and shall pay to Landlord a Landlord supervision fee of five
percent (5%) of the cost of the Alterations.  The construction of the initial
improvements to the Premises shall be governed by the terms of the Tenant Work
Letter and not the terms of this Article 8.
 
8.2           Manner of Construction.  Landlord may impose, as a condition of
its consent to all Alterations or repairs of the Premises, such requirements as
Landlord in its reasonable discretion may deem desirable, including, but not
limited to, the requirement that Tenant utilize for such purposes only
contractors, materials, mechanics and materialmen approved by Landlord;
provided, however, Landlord may impose such requirements as Landlord may
determine, in its sole and absolute discretion, with respect to any work
affecting the structural components of the Buildings or Systems and Equipment
(including designating specific contractors to perform such work).  Tenant shall
construct such Alterations and perform such repairs in compliance with any and
all applicable rules and regulations of any federal, state, county or municipal
code or ordinance (including, without limitation, California Energy Code, Title
24) and pursuant to a valid building permit, issued by the city in which the
Buildings are located, and in conformance with Landlord's construction rules and
regulations.  Landlord's approval of the plans, specifications and working
drawings for Tenant's Alterations shall create no responsibility or liability on
the part of Landlord for their completeness, design sufficiency, or compliance
with all laws, rules and regulations of governmental agencies or authorities. 
All work with respect to any Alterations must be done in a good and workmanlike
manner and diligently prosecuted to completion to the end that the Premises
shall at all times be a complete unit except during the period of work.  Tenant
shall cause all Alterations to be performed in such manner as not to obstruct
access by any person to the Buildings or Project or the common areas, and as not
to obstruct the business of Landlord or other tenants of the Project, or
interfere with the labor force working at the Project.  If Tenant makes any
Alterations, Tenant agrees to carry "Builder's All Risk" insurance in an amount
approved by Landlord covering the construction of such Alterations, and such
other insurance as Landlord may reasonably require consistent with the practices
of institutional owners of the Comparable Buildings, it being understood and
agreed that all of such Alterations shall be insured by Tenant pursuant to
Article 10 below immediately upon completion thereof.  Landlord may, in its
discretion, require Tenant to obtain a lien and completion bond or some
alternate form of security satisfactory to Landlord in an amount sufficient to
ensure the lien-free completion of such Alterations and naming Landlord as a
co-obligee.  Upon completion of any Alterations, Tenant shall (i) cause a Notice
of Completion to be recorded in the office of the Recorder of the county in
which the Project is located in accordance with Section 8182 of the Civil Code
of the State of California or any successor statute, (ii) deliver to the
management office of the Buildings a reproducible copy of the "as built"
drawings of the Alterations, and (iii) deliver to Landlord evidence of payment,
contractors' affidavits and full and final waivers of all liens for labor,
services or materials.
 
8.3           Landlord's Property.  All Alterations, improvements, fixtures
and/or equipment which may be installed or placed in or about the Premises shall
be at the sole cost of Tenant and shall be and become the property of Landlord. 
Furthermore, Landlord may require that Tenant remove any improvement (including
the initial Tenant Improvements installed pursuant to the Tenant Work Letter) or
Alterations upon the expiration or early termination of the Lease Term, and
repair any damage to the Premises and Buildings caused by such removal;
provided, however, with respect to any improvements (including the initial
Tenant Improvements installed pursuant to the Tenant Work Letter) or Alterations
made or caused to be made by Tenant with Landlord's consent, Tenant shall have
no obligation to remove any such improvements or Alterations unless at the time
Landlord approved the final working drawings for any such improvements or
Alterations, Landlord, by written notice to Tenant, identified those
improvements or Alterations which Landlord would require Tenant to remove at the
expiration or earlier termination of this Lease, in which event Tenant shall
remove such identified improvements and/or Alterations (as the case may be) on
or before the expiration of the Lease Term (as may be extended) and repair any
damage resulting from such removal.  If Tenant fails to complete such removal
and/or to repair by the end of the Lease Term, Landlord may do so and may charge
the cost thereof to Tenant.
 

 -11-
MARINA VILLAGE
[Biotime]

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

8.4           Wi-Fi Network.  Without limiting the generality of the foregoing,
if Tenant desires to install wireless intranet, Internet and communications
network ("Wi-Fi Network") in the Premises for the use by Tenant and its
employees, then the same shall be subject to the provisions of this Section 8.4
(in addition to the other provisions of this Article 8).  If Landlord consents
to Tenant's installation of such Wi-Fi Network, Tenant shall, in accordance with
Article 15 below, remove the Wi-Fi Network from the Premises prior to the
termination of the Lease.  Tenant shall use the Wi-Fi Network so as not to cause
any interference to other tenants in the Buildings or to other tenants at the
Project or with any other tenant's communication equipment, and not to damage
the Buildings or Project or interfere with the normal operation of the Buildings
or Project, and Tenant hereby agrees to indemnify, defend and hold Landlord
harmless from and against any and all claims, costs, damages, expenses and
liabilities (including attorneys' fees) arising out of Tenant's failure to
comply with the provisions of this Section 8.4, except to the extent same is
caused by the gross negligence or willful misconduct of Landlord and which is
not covered by the insurance carried by Tenant under this Lease (or which would
not be covered by the insurance required to be carried by Tenant under this
Lease).  Should any interference occur, Tenant shall take all necessary steps as
soon as reasonably possible following such occurrence to correct such
interference.  If such interference continues for more than three (3) business
days, Tenant shall immediately cease operating such Wi-Fi Network until such
interference is corrected or remedied to Landlord’s satisfaction.  Tenant
acknowledges that Landlord has granted and/or may grant telecommunication rights
to other tenants and occupants of the Buildings and Project and to
telecommunication service providers and in no event shall Landlord be liable to
Tenant for any interference of the same with such Wi-Fi Network.  Landlord makes
no representation that the Wi-Fi Network will be able to receive or transmit
communication signals without interference or disturbance.  Tenant shall (i) be
solely responsible for any damage caused as a result of the Wi-Fi Network, (ii)
promptly pay any tax, license or permit fees charged pursuant to any laws or
regulations in connection with the installation, maintenance or use of the Wi-Fi
Network and comply with all precautions and safeguards recommended by all
governmental authorities, (iii) pay for all necessary repairs, replacements to
or maintenance of the Wi-Fi Network, and (iv) be responsible for any
modifications, additions or repairs to the Buildings or Project, including
without limitation, Buildings or Project systems or infrastructure, which are
required by reason of the installation, operation or removal of Tenant’s Wi-Fi
Network.  Should Landlord be required to retain professionals to research any
interference issues that may arise and confirm Tenant's compliance with the
terms of this Section 8.4, Tenant shall reimburse Landlord for the costs
incurred by Landlord in connection with Landlord's retention of such
professionals, the research of such interference issues and confirmation of
Tenant's compliance with the terms of this Section 8.4 within twenty (20) days
after the date Landlord submits to Tenant an invoice for such costs.  This
reimbursement obligation is in addition to, and not in lieu of, any rights or
remedies Landlord may have in the event of a breach or default by Tenant under
this Lease.
 
ARTICLE 9
 
COVENANT AGAINST LIENS
 
Tenant has no authority or power to cause or permit any lien or encumbrance of
any kind whatsoever, whether created by act of Tenant, operation of law or
otherwise, to attach to or be placed upon the Project, Buildings or Premises,
and any and all liens and encumbrances created by Tenant shall attach to
Tenant's interest only.  Landlord shall have the right at all times to post and
keep posted on the Premises any notice which it deems necessary for protection
from such liens.  Tenant shall not cause or permit any lien of mechanics or
materialmen or others to be placed against the Project, the Buildings or the
Premises with respect to work or services claimed to have been performed for or
materials claimed to have been furnished to Tenant or the Premises, and, in case
of any such lien attaching or notice of any lien, Tenant shall cause it to be
promptly released and removed of record.  If any such lien is not released and
removed within five (5) business days after notice of such lien is delivered by
Landlord to Tenant, then Landlord may, at its option, take all action necessary
to release and remove such lien, without any duty to investigate the validity
thereof, and all sums, costs and expenses, including reasonable attorneys' fees
and costs, incurred by Landlord in connection with such lien shall be deemed
Additional Rent under this Lease and shall immediately be due and payable by
Tenant.
 
ARTICLE 10
 
INDEMNIFICATION AND INSURANCE
 
10.1        Indemnification and Waiver.  Tenant hereby assumes all risk of
damage to property and injury to persons, in, on, or about the Premises from any
cause whatsoever and agrees that Landlord, and its partners and subpartners, and
their respective officers, agents, property managers, servants, employees, and
independent contractors (collectively, "Landlord Parties") shall not be liable
for, and are hereby released from any responsibility for, any damage to property
or injury to persons or resulting from the loss of use thereof, which damage or
injury is sustained by Tenant or by other persons claiming through Tenant. 
Tenant shall indemnify, defend, protect, and hold harmless the Landlord Parties
from any and all loss, cost, damage, expense and liability (including without
limitation court costs and reasonable attorneys' fees) (collectively, the
"Claims") incurred in connection with or arising from any cause in, on or about
the Premises (including, without limitation, Tenant's installation, placement
and removal of Alterations, improvements, fixtures and/or equipment in, on or
about the Premises), and any acts, omissions or negligence of Tenant or of any
person claiming by, through or under Tenant, or of the contractors, agents,
servants, employees, licensees or invitees of Tenant or any such person, in, on
or about the Premises, the Buildings and Project.  Notwithstanding the foregoing
provisions of this Section 10.1 to the contrary, (i) except for lost profits,
loss of business or other consequential damages (collectively, "Consequential
Damages") incurred or suffered by Tenant or Tenant's contractors, agents,
employees, licensees or invitees, the assumption of risk and release by Tenant
set forth hereinabove shall not apply to any Claims to the extent resulting from
the negligence or willful misconduct of Landlord or the Landlord Parties and not
insured or required to be insured by Tenant under this Lease (collectively, the
"Excluded Claims"), and (ii) Tenant's indemnity of Landlord hereinabove shall
not apply to (A) any Excluded Claims, (B) any loss of or damage to Landlord's
property to the extent Landlord has waived such loss or damage pursuant to
Section 10.4 below, or (C) any Consequential Damages suffered by Landlord or the
Landlord Parties.  The provisions of this Section 10.1 shall survive the
expiration or sooner termination of this Lease.
 

 -12-
MARINA VILLAGE
[Biotime]

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

10.2        Landlord's Insurance; Tenant's Compliance with Landlord's Fire and
Casualty Insurance.  Landlord shall, from and after the date hereof until the
expiration of the Lease Term (as may be extended), maintain in effect the
following insurance:  (i) physical damage insurance (including a rental loss
endorsement) providing coverage in the event of fire, vandalism, malicious
mischief and all other risks normally covered under "special form" policies in
the geographical area of the Project, covering the Buildings (excluding, at
Landlord's option, the property required to be insured by Tenant pursuant to
Section 10.3.2 below) in an amount not less than the full replacement value
(less commercially reasonable deductibles) of the Buildings, together with such
other risks as Landlord may from time to time determine (provided however, that
Landlord shall have the right, but not the obligation, to obtain earthquake
and/or flood insurance); and (ii) commercial general liability insurance
insuring against claims of bodily injury, personal injury or property damage
arising out of Landlord's operations, contractual liabilities, or use of the
Project.  Such coverages may be carried under one or more blanket and/or
umbrella insurance policies so long as the coverages required under this Lease
with respect to the Buildings and/or Project are not reduced or impaired as a
result thereof.  Tenant shall, at Tenant's expense, comply as to the Premises
with all insurance company requirements pertaining to the use of the Premises. 
If Tenant's conduct or use of the Premises causes any increase in the premium
for such insurance policies carried by Landlord, then Tenant shall reimburse
Landlord for any such increase. Tenant, at Tenant's expense, shall comply with
all rules, orders, regulations or requirements of the American Insurance
Association (formerly the National Board of Fire Underwriters) and with any
similar body with respect to Tenant's use of and/or activities in the Premises
and the Project.
 
10.3        Tenant's Insurance.  Tenant shall maintain the following coverages
in the following amounts.
 
10.3.1        Commercial General Liability Insurance covering the insured
against claims of bodily injury, personal injury and property damage arising out
of Tenant's operations, assumed liabilities or use of the Premises, including a
Broad Form Commercial General Liability endorsement covering the insuring
provisions of this Lease and the performance by Tenant of the indemnity
agreements set forth in Section 10.1 above, (and with owned and non-owned
automobile liability coverage, and liquor liability coverage if alcoholic
beverages are served on the Premises) for limits of liability not less than:
 
Bodily Injury and
$5,000,000 each occurrence
Property Damage Liability
$5,000,000 annual aggregate
   
Personal Injury Liability
$5,000,000 each occurrence
 
$5,000,000 annual aggregate
 
0% Insured's participation

 
10.3.2         Physical Damage Insurance covering (i) all furniture, trade
fixtures, equipment, merchandise and all other items of Tenant's property on the
Premises installed by, for, or at the expense of Tenant, (ii) the Tenant
Improvements, including any Tenant Improvements which Landlord permits to be
installed above the ceiling of the Premises or below the floor of the Premises,
and (iii) all other improvements, alterations and additions to the Premises,
including any improvements, alterations or additions installed at Tenant's
request above the ceiling of the Premises or below the floor of the Premises. 
Such insurance shall be written on a "physical loss or damage" basis under a
"special form" policy, for the full replacement cost value new without deduction
for depreciation of the covered items and in amounts that meet any co-insurance
clauses of the policies of insurance and shall include a vandalism and malicious
mischief endorsement, sprinkler leakage coverage and earthquake sprinkler
leakage coverage.
 
10.3.3         Workers' compensation insurance as required by law.
 
10.3.4         Loss-of-income, business interruption and extra-expense insurance
in such amounts as will reimburse Tenant for direct and indirect loss of
earnings attributable to all perils commonly insured against by prudent tenants
or attributable to prevention of loss of access to the Premises or to the
Buildings as a result of such perils; provided, however, that Tenant may
self-insure with regard to the risks described in this Section 10.3.4, provided
that in all instances such self-insurance shall be deemed to contain all of the
terms and conditions applicable to such insurance as required in this Section
10.3.4, and Tenant hereby waives any right it may have against Landlord with
respect to any damage or loss that would otherwise have been covered by the
insurance described in this Section 10.3.4.
 
10.3.5        Tenant shall carry comprehensive automobile liability insurance
having a combined single limit of not less than One Million Dollars
($1,000,000.00) per occurrence and insuring Tenant against liability for claims
arising out of ownership, maintenance or use of any automobiles owned or hired
by Tenant (but not Tenant's employees).
 

 -13-
MARINA VILLAGE
[Biotime]

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

10.3.6       Form of Policies. The minimum limits of policies of insurance
required of Tenant under this Lease shall in no event limit the liability of
Tenant under this Lease. Such insurance shall: (i) name Landlord (and any
mortgagee or ground or underlying lessor of Landlord after Landlord's written
request therefor) as an additional insured; (ii) specifically cover the
liability assumed by Tenant under this Lease, including, but not limited to,
Tenant's obligations under Section 10.1 above; (iii) be issued by an insurance
company having a rating of not less than A-X in Best's Insurance Guide or which
is otherwise acceptable to Landlord and licensed to do business in the state in
which the Project is located; (iv) be primary insurance as to all claims
thereunder and provide that any insurance carried by Landlord is excess and is
non-contributing with any insurance requirement of Tenant; (v) provide that said
insurance shall not be canceled or coverage changed unless thirty (30) days'
prior written notice shall have been given to Landlord and any mortgagee or
ground or underlying lessor of Landlord; (vi) contain a cross-liability
endorsement or severability of interest clause acceptable to Landlord; and (vii)
with respect to the insurance required in Sections 10.3.1 and 10.3.2 above, have
deductible amounts not exceeding Five Thousand Dollars ($5,000.00). Tenant shall
deliver such policies or certificates thereof to Landlord on or before the Lease
Commencement Date and at least thirty (30) days before the expiration dates
thereof. If Tenant shall fail to procure such insurance, or to deliver such
policies or certificate, within such time periods, Landlord may, at its option,
in addition to all of its other rights and remedies under this Lease, and
without regard to any notice and cure periods set forth in Section 19.1, procure
such policies for the account of Tenant, and the cost thereof shall be paid to
Landlord as Additional Rent within ten (10) days after delivery of bills
therefor.
 
10.4        Subrogation.  Landlord and Tenant agree to have their respective
insurance companies issuing property damage insurance waive any rights of
subrogation that such companies may have against Landlord or Tenant, as the case
may be.  Landlord and Tenant hereby waive any right that either may have against
the other on account of any loss or damage to their respective property to the
extent such loss or damage is insurable under policies of insurance for fire and
all risk coverage, theft, public liability, or other similar insurance.
 
10.5        Additional Insurance Obligations.  Tenant shall carry and maintain
during the entire Lease Term, at Tenant's sole cost and expense, increased
amounts of the insurance required to be carried by Tenant pursuant to this
Article 10, and such other reasonable types of insurance coverage and in such
reasonable amounts covering the Premises and Tenant's operations therein, as may
be reasonably requested by Landlord, but in no event shall such increased
amounts of insurance or such other reasonable types of insurance be in excess of
that generally required by institutional owners of the Comparable Buildings and
in no event may Landlord increase the amounts of the insurance required to be
carried by Tenant hereunder more than once during the initial Lease Term and
once during the Option Term (if applicable).
 
ARTICLE 11
 
DAMAGE AND DESTRUCTION
 
11.1        Repair of Damage to Premises by Landlord.  Tenant shall promptly
notify Landlord of any damage to the Premises resulting from fire or any other
casualty.  If the Premises or any common areas of the Buildings or Project
serving or providing access to the Premises shall be damaged by fire or other
casualty, Landlord shall promptly and diligently, subject to reasonable delays
for insurance adjustment or other matters beyond Landlord's reasonable control,
and subject to all other terms of this Article 11, restore the base, shell, and
core of the Premises and such common areas.  Such restoration shall be to
substantially the same condition of the base, shell, and core of the Premises
and common areas prior to the casualty, except for modifications required by
zoning and building codes and other laws or by the holder of a mortgage on the
Project and/or the Buildings, or the lessor of a ground or underlying lease with
respect to the Buildings, or any other modifications to the common areas deemed
desirable by Landlord, provided access to the Premises and any common restrooms
serving the Premises shall not be materially impaired.  Upon the occurrence of
any damage to the Premises, Tenant shall assign to Landlord (or to any party
designated by Landlord) all insurance proceeds payable to Tenant under Tenant's
insurance required under Section 10.3 of this Lease, and Landlord shall repair
any damage to the tenant improvements and alterations installed in the Premises
and shall return such tenant improvements and alterations to their original
condition; provided that if the costs of such repair of such tenant improvements
and Alterations by Landlord exceeds the amount of insurance proceeds received by
Landlord therefor from Tenant's insurance carrier, as assigned by Tenant, the
excess costs of such repairs shall be paid by Tenant to Landlord prior to
Landlord's repair of the damage.  In connection with such repairs and
replacements of any such tenant improvements and Alterations, Tenant shall,
prior to Landlord's commencement of such improvement work, submit to Landlord,
for Landlord's review and approval, all plans, specifications and working
drawings relating thereto, and Landlord shall select the contractors to perform
such improvement work.  Landlord shall not be liable for any inconvenience or
annoyance to Tenant or its visitors, or injury to Tenant's business resulting in
any way from such damage or the repair thereof; provided however, that if such
fire or other casualty shall have damaged the Premises or common areas necessary
to Tenant's occupancy, and if such damage is not the result of the negligence or
willful misconduct of Tenant or Tenant's employees, contractors, licensees, or
invitees, Landlord shall allow Tenant a proportionate abatement of Base Rent and
the applicable Tenant's Share of Operating Expenses, Tax Expenses and Utilities
Costs to the extent Landlord is reimbursed from the proceeds of rental
interruption insurance purchased by Landlord as part of Operating Expenses,
during the time and to the extent the Premises are unfit for occupancy for the
purposes permitted under this Lease, and not occupied by Tenant as a result
thereof.
 
11.2        Landlord's Option to Repair.  Notwithstanding Section 11.1 above to
the contrary, Landlord may elect not to rebuild and/or restore the Premises, the
Buildings and/or any other portion of the Project and instead terminate this
Lease by notifying Tenant in writing of such termination within sixty (60) days
after the date Landlord becomes aware of such damage, such notice to include a
termination date giving Tenant ninety (90) days to vacate the Premises, but
Landlord may so elect only if the Buildings shall be damaged by fire or other
casualty or cause, whether or not the Premises are affected, and one or more of
the following conditions is present:  (i) repairs cannot reasonably be
substantially completed within one hundred twenty (120) days after the date of
such damage (when such repairs are made without the payment of overtime or other
premiums); (ii) the holder of any mortgage on the Project and/or the Buildings
or ground or underlying lessor with respect to the Project and/or the Buildings
shall require that the insurance proceeds or any portion thereof be used to
retire the mortgage debt, or shall terminate the ground or underlying lease, as
the case may be; or (iii) the damage is not fully covered, except for deductible
amounts, by Landlord's insurance policies, and the cost of repairing such
uninsured or underinsured damage, excluding deductibles other than deductibles
for earthquake insurance, exceeds $100,000.00.  In addition, if the Premises or
the Buildings are destroyed or damaged to any substantial extent during the last
year of the Lease Term, then notwithstanding anything contained in this Article
11, Landlord shall have the option to terminate this Lease by giving written
notice to Tenant of the exercise of such option within thirty (30) days after
such damage, in which event this Lease shall cease and terminate as of the date
of such notice.  Upon any such termination of this Lease pursuant to this
Section 11.2, Tenant shall pay the Base Rent and Additional Rent, properly
apportioned up to such date of termination, but subject to abatement pursuant to
Section 11.1 above as and to the extent applicable, and both parties hereto
shall thereafter be discharged of all further obligations under this Lease,
except for those obligations which expressly survive the expiration or earlier
termination of the Lease Term.
 

 -14-
MARINA VILLAGE
[Biotime]

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

11.3       Waiver of Statutory Provisions.  The provisions of this Lease,
including this Article 11, constitute an express agreement between Landlord and
Tenant with respect to any and all damage to, or destruction of, all or any part
of the Premises, the Buildings or any other portion of the Project, and any
statute or regulation of the state in which the Project is located, including,
without limitation, Sections 1932(2) and 1933(4) of the California Civil Code,
with respect to any rights or obligations concerning damage or destruction in
the absence of an express agreement between the parties, and any other statute
or regulation, now or hereafter in effect, shall have no application to this
Lease or any damage or destruction to all or any part of the Premises, the
Buildings or any other portion of the Project.

ARTICLE 12
 
CONDEMNATION
 
12.1        Permanent Taking.  If the whole or any part of the Premises,
Buildings or Project shall be taken by power of eminent domain or condemned by
any competent authority for any public or quasi-public use or purpose, or if any
adjacent property or street shall be so taken or condemned, or reconfigured or
vacated by such authority in such manner as to require the use, reconstruction
or remodeling of any part of the Premises, Buildings or Project, or if Landlord
shall grant a deed or other instrument in lieu of such taking by eminent domain
or condemnation, Landlord shall have the option to terminate this Lease upon
ninety (90) days' notice, provided such notice is given no later than one
hundred eighty (180) days after the date of such taking, condemnation, deed or
other instrument; provided, however, that (i) Landlord shall only have the right
to terminate this Lease as provided herein if Landlord terminates the leases of
all tenants in the Building similarly affected by the taking which leases
contain similar termination rights in favor of Landlord as provided herein, and
(ii) to the extent that the Premises are not adversely affected by such taking
and Landlord continues to operate the Building as an office, technology or
laboratory building, Landlord shall not terminate this Lease.  If more than
twenty-five percent (25%) of the rentable square feet of the Premises is taken,
or if access to the Premises is substantially impaired, Tenant shall have the
option to terminate this Lease upon thirty (30) days' notice, provided such
notice is given no later than one hundred eighty (180) days after the date of
such taking.  Landlord shall be entitled to receive the entire award or payment
in connection therewith, except that Tenant shall have the right to file any
separate claim available to Tenant for any taking of Tenant's personal property
and fixtures belonging to Tenant and removable by Tenant upon expiration of the
Lease Term pursuant to the terms of this Lease, and for moving expenses, so long
as such claim does not diminish the award available to Landlord, or its ground
lessor or mortgagee with respect to the Project, and such claim is payable
separately to Tenant.  All Rent shall be apportioned as of the date of such
termination, or the date of such taking, whichever shall first occur.  If any
part of the Premises shall be taken, and this Lease shall not be so terminated,
the Base Rent and the applicable Tenant's Share of Operating Expenses, Tax
Expenses and Utilities Costs shall be proportionately abated.  Tenant hereby
waives any and all rights it might otherwise have pursuant to Section 1265.130
of The California Code of Civil Procedure.
 
12.2        Temporary Taking.  Notwithstanding anything to the contrary
contained in this Article 12, in the event of a temporary taking of all or any
portion of the Premises for a period of one hundred and eighty (180) days or
less, then this Lease shall not terminate but the Base Rent and the applicable
Tenant's Share of Operating Expenses, Tax Expenses and Utilities Costs shall be
abated for the period of such taking in proportion to the ratio that the amount
of rentable square feet of the Premises taken bears to the total rentable square
feet of the Premises.  Landlord shall be entitled to receive the entire award
made in connection with any such temporary taking.
 
ARTICLE 13
 
COVENANT OF QUIET ENJOYMENT
 
Landlord covenants that provided Tenant is not in default under this Lease
beyond the expiration of any applicable notice and cure periods, Tenant shall,
during the Lease Term, peaceably and quietly have, hold and enjoy the Premises
subject to the terms, covenants, conditions, and agreements hereof without
interference by Landlord or any persons lawfully claiming by or through
Landlord.  The foregoing covenant is in lieu of any other covenant express or
implied.
 

 -15-
MARINA VILLAGE
[Biotime]

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

ARTICLE 14
 
ASSIGNMENT AND SUBLETTING
 
14.1       Transfers.  Subject to Sections 14.7 and 14.8 below, Tenant shall
not, without the prior written consent of Landlord, assign, mortgage, pledge,
hypothecate, encumber, or permit any lien to attach to, or otherwise transfer,
this Lease or any interest hereunder, permit any assignment or other such
foregoing transfer of this Lease or any interest hereunder by operation of law,
sublet the Premises or any part thereof, or permit the use of the Premises by
any persons other than Tenant and its employees and contractors (all of the
foregoing are hereinafter sometimes referred to collectively as "Transfers" and
any person to whom any Transfer is made or sought to be made is hereinafter
sometimes referred to as a "Transferee").  If Tenant shall desire Landlord's
consent to any Transfer, Tenant shall notify Landlord in writing, which notice
(the "Transfer Notice") shall include (i) the proposed effective date of the
Transfer, which shall not be less than thirty (30) days nor more than one
hundred eighty (180) days after the date of delivery of the Transfer Notice,
(ii) a description of the portion of the Premises to be transferred (the
"Subject Space"), (iii) all of the terms of the proposed Transfer, the name and
address of the proposed Transferee, and a copy of all existing and/or proposed
documentation pertaining to the proposed Transfer, (iv) current financial
statements of the proposed Transferee certified by an officer, partner or owner
thereof, and (v) such other information as Landlord may reasonably require.  Any
Transfer made without Landlord's prior written consent shall, at Landlord's
option, be null, void and of no effect, and shall, at Landlord's option,
constitute a default by Tenant under this Lease.  Whether or not Landlord shall
grant consent, within thirty (30) days after written request by Landlord, Tenant
shall pay to Landlord Two Thousand Five Hundred Dollars ($2,500.00) to reimburse
Landlord for its review and processing fees, and Tenant shall also reimburse
Landlord for any reasonable legal fees incurred by Landlord in connection with
Tenant's proposed Transfer.
 
14.2        Landlord's Consent.  Subject to Sections 14.7 and 14.8 below,
Landlord shall not unreasonably withhold its consent to any proposed Transfer on
the terms specified in the Transfer Notice.  The parties hereby agree that it
shall be reasonable under this Lease and under any Applicable Law for Landlord
to withhold consent to any proposed Transfer where one or more of the following
apply, without limitation as to other reasonable grounds for withholding
consent:
 
14.2.1         The Transferee is of a character or reputation or engaged in a
business which is not consistent with the quality of the Buildings or Project;
 
14.2.2         The Transferee intends to use the Subject Space for purposes
which are not permitted under this Lease;
 
14.2.3        The Transferee is either a governmental agency or instrumentality
thereof;
 
14.2.4        The Transfer will result in more than a reasonable and safe number
of occupants per floor within the Subject Space;
 
14.2.5        The Transferee is not a party of reasonable financial worth and/or
financial stability in light of the responsibilities involved under the Lease on
the date consent is requested;
 
14.2.6        The proposed Transfer would cause Landlord to be in violation of
another lease or agreement to which Landlord is a party, or would give an
occupant of the Project a right to cancel its lease; or
 
14.2.7        Either the proposed Transferee, or any person or entity which
directly or indirectly, controls, is controlled by, or is under common control
with, the proposed Transferee, (i) occupies space in the Project at the time of
the request for consent and space of comparable size to the Subject Space is
available for lease in the Project on a direct basis from Landlord, or (ii) is
negotiating with Landlord to lease space in the Project at such time and space
of comparable size to the Subject Space is available for lease in the Project on
a direct basis from Landlord.
 
If Landlord consents to any Transfer pursuant to the terms of this Section 14.2
(and does not exercise any recapture rights Landlord may have under Section 14.4
below), Tenant may within six (6) months after Landlord's consent, enter into
such Transfer of the Premises or portion thereof, upon substantially the same
terms and conditions as are set forth in the Transfer Notice furnished by Tenant
to Landlord pursuant to Section 14.1 above, provided that if there are any
changes in the terms and conditions from those specified in the Transfer Notice
such that Landlord would initially have been entitled to refuse its consent to
such Transfer under this Section 14.2, Tenant shall again submit the Transfer to
Landlord for its approval and other action under this Article 14 (including
Landlord's right of recapture, if any, under Section 14.4 of this Lease).
 
14.3        Transfer Premium.  Subject to Sections 14.7 and 14.8 below, if
Landlord consents to a Transfer, as a condition thereto which the parties hereby
agree is reasonable, Tenant shall pay to Landlord fifty percent (50%) of any
Transfer Premium received by Tenant from such Transferee.  "Transfer Premium"
shall mean all rent, additional rent or other consideration payable by such
Transferee in excess of the Rent and Additional Rent payable by Tenant under
this Lease on a per rentable square foot basis if less than all of the Premises
is transferred, after deducting the reasonable expenses incurred by Tenant for
(i) any reasonable changes, alterations and improvements to the Premises in
connection with the Transfer (but only to the extent approved by Landlord), and
(ii) any reasonable brokerage commissions in connection with the Transfer
(collectively, the "Subleasing Costs").  Transfer Premium shall also include,
but not be limited to, key money and bonus money paid by Transferee to Tenant in
connection with such Transfer, and any payment in excess of fair market value
for services rendered by Tenant to Transferee or for assets, fixtures,
inventory, equipment, or furniture transferred by Tenant to Transferee in
connection with such Transfer.
 
14.4        Landlord's Option as to Subject Space.  Notwithstanding anything to
the contrary contained in this Article 14 (but subject to Sections 14.7 and 14.8
below), Landlord shall have the option, by giving written notice to Tenant
within thirty (30) days after receipt of any Transfer Notice, to recapture the
Subject Space.  Such recapture notice shall terminate this Lease with respect to
the Subject Space as of the date stated in the Transfer Notice as the effective
date of the proposed Transfer until the last day of the term of the Transfer as
set forth in the Transfer Notice; provided, however, such recapture and
termination right shall only apply with respect to any proposed assignment, or
any sublease, which, when aggregated with all subleases then in effect to
non-Affiliates, pertains to more than twenty-five percent (25%) of the
Premises.  If this Lease is terminated with respect to less than the entire
Premises, the Rent reserved herein shall be prorated on the basis of the
rentable square feet retained by Tenant in proportion to the rentable square
feet contained in the Premises, and this Lease as so amended shall continue
thereafter in full force and effect, and upon request of either party, the
parties shall execute written confirmation of the same.  If Landlord declines,
or fails to elect in a timely manner to recapture the Subject Space under this
Section 14.4, then, provided Landlord has consented to the proposed Transfer,
Tenant shall be entitled to proceed to transfer the Subject Space to the
proposed Transferee, subject to provisions of the last paragraph of Section 14.2
above.  Tenant shall not incur or be liable for any commissions, costs, fees or
expenses payable to third parties resulting from Landlord's recapture of any
Subject Space from Tenant.
 

 -16-
MARINA VILLAGE
[Biotime]

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

14.5        Effect of Transfer.  If Landlord consents to a Transfer: (i) the
terms and conditions of this Lease shall in no way be deemed to have been waived
or modified; (ii) such consent shall not be deemed consent to any further
Transfer by either Tenant or a Transferee; (iii) Tenant shall deliver to
Landlord, promptly after execution, an original executed copy of all
documentation pertaining to the Transfer in form reasonably acceptable to
Landlord; and (iv) no Transfer relating to this Lease or agreement entered into
with respect thereto, whether with or without Landlord's consent, shall relieve
Tenant or any guarantor of the Lease from liability under this Lease.  Landlord
or its authorized representatives shall have the right at all reasonable times
to audit the books, records and papers of Tenant relating to any Transfer, and
shall have the right to make copies thereof.  If the Transfer Premium respecting
any Transfer shall be found understated, Tenant shall, within thirty (30) days
after demand, pay the deficiency and Landlord's costs of such audit.
 
14.6        Additional Transfers.  For purposes of this Lease, the term
"Transfer" shall also include the following (subject, however, to the provisions
of Section 14.7 below): (i) if Tenant is a partnership or limited liability
company, the withdrawal or change, voluntary, involuntary or by operation of
law, of more than fifty percent (50%) of the partners or members, or transfer of
more than fifty percent (50%) of the partnership or membership interests, within
a twelve (12)-month period, or the dissolution of the partnership without
immediate reconstitution thereof; and (ii) if Tenant is a closely held
corporation (i.e., whose stock is not publicly held and not traded through an
exchange or over the counter), (A) the dissolution, merger, consolidation or
other reorganization of Tenant, (B) the sale or other transfer of more than an
aggregate of fifty percent (50%) of the voting shares of Tenant (other than to
immediate family members by reason of gift or death), within a twelve (12)-month
period, or (C) the sale, mortgage, hypothecation or pledge of more than an
aggregate of fifty percent (50%) of the value of the unencumbered assets of
Tenant within a twelve (12) month period.
 
14.7        Permitted Transfers to Affiliates. Notwithstanding the foregoing
provisions of this Article 14 to the contrary, the assignment or subletting by
Tenant of all or any portion of this Lease or the Premises to (i) a parent or
subsidiary of Tenant, or (ii) any person or entity which controls, is controlled
by or under common control with Tenant, or (iii) any entity which purchases all
or substantially all of the assets and/or stock of Tenant, or (iv) a successor
to Tenant or any of the foregoing entities by purchase, merger, consolidation or
reorganization (all such persons or entities described in (i), (ii), (iii) and
(iv) being sometimes hereinafter referred to as "Affiliates") shall not be
deemed a Transfer under this Article 14, and thus shall not be subject to the
requirement of obtaining Landlord's consent thereto in Sections 14.1 and 14.2
above, or Landlord's right to receive any Transfer Premium pursuant to Section
14.3 above, or recapture right in Section 14.4 above, provided that:
 
14.7.1      any such Affiliate was not formed, and such transaction was not
entered into, as a subterfuge to (i) avoid the obligations of this Article 14,
or (ii) adversely affect the ability of Tenant to satisfy its obligations under
this Lease;
 
14.7.2         Tenant gives Landlord notice of any such assignment or sublease
to an Affiliate within ten (10) business days after the effective date of any
such assignment or sublease;
 
14.7.3         the successor of Tenant and Tenant have as of the effective date
of this Lease and/or the date of any such assignment or sublease a tangible net
worth, in the aggregate, computed in accordance with generally accepted
accounting principles (but excluding goodwill as an asset), which is sufficient
to meet the obligations of Tenant under this Lease;
 
14.7.4         any such assignment or sublease shall be subject and subordinate
to all of the terms and provisions of this Lease, and such assignee or sublessee
shall assume, in a written document reasonably satisfactory to Landlord and
delivered to Landlord within ten (10) business days after the effective date of
such assignment or sublease, all the obligations of Tenant under this Lease with
respect to the Subject Space which is the subject of such Transfer (other than
the amount of Base Rent and the applicable Tenant's Share of Excess Operating
Expenses, Tax Expenses and Utilities Costs payable by Tenant with respect to a
sublease); and
 
14.7.5        Tenant shall remain fully liable for all obligations to be
performed by Tenant under this Lease.
 
"Control", as used in this Section 14.7, shall mean the possession, direct or
indirect, of the power to cause the direction of the management and policies of
a person or entity, or ownership of any sort, whether through the ownership of
voting securities, by contract or otherwise.
 
14.8        Business Affiliates.  Notwithstanding anything to the contrary
contained in the foregoing provisions of this Article 14, Tenant shall have the
right, without being subject to Landlord's prior consent, Landlord's right to
receive any Transfer Premium pursuant to Section 14.3 above, or Landlord's
recapture option in Section 14.4 above, but upon at least ten (10) days' prior
written notice to Landlord, to sublease, license or otherwise permit occupancy
of portions of the Premises to other entities and/or individuals who have an
ongoing business relationship with Tenant, including subsidiaries of Tenant
(each a "Business Affiliate"), which sublease, license or occupancy agreement,
as the case may be, to a Business Affiliate shall be on and subject to all of
the following conditions:  (i) all such Business Affiliates shall be of a
reputation comparable to the reputation of other tenants of the Building; (ii)
all such Business Affiliates shall use the Premises for the Permitted Use and
otherwise in conformity with all of the applicable provisions of this Lease;
(iii) each such sublease, license or occupancy agreement is not a subterfuge by
Tenant to avoid its obligations under this Article 14; (iv) there shall be no
separate exterior demising walls which separate the space which is the subject
of such sublease, license or occupancy agreement from the balance of the
Premises or separate exterior entrances to the space which is the subject of
such sublease, license or occupancy agreement; and (v) each such sublease,
license and occupancy agreement shall be subject to and subordinate to all of
the terms and provisions of this Lease.  No such sublease, license or occupancy
agreement, as the case may be, shall relieve Tenant from any liability under
this Lease.
 

 -17-
MARINA VILLAGE
[Biotime]

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

ARTICLE 15
 
SURRENDER; OWNERSHIP AND REMOVAL OF PERSONAL PROPERTY
 
15.1        Surrender of Premises.  No act or thing done by Landlord or any
agent or employee of Landlord during the Lease Term shall be deemed to
constitute an acceptance by Landlord of a surrender of the Premises unless such
intent is specifically acknowledged in a writing signed by Landlord.  The
delivery of keys to the Premises to Landlord or any agent or employee of
Landlord shall not constitute a surrender of the Premises or effect a
termination of this Lease, whether or not the keys are thereafter retained by
Landlord, and notwithstanding such delivery Tenant shall be entitled to the
return of such keys at any reasonable time upon request until this Lease shall
have been properly terminated.  The voluntary or other surrender of this Lease
by Tenant, whether accepted by Landlord or not, or a mutual termination hereof,
shall not work a merger, and at the option of Landlord shall operate as an
assignment to Landlord of all subleases or subtenancies affecting the Premises.
 
15.2        Removal of Tenant Property by Tenant.  Upon the expiration of the
Lease Term, or upon any earlier termination of this Lease, Tenant shall, subject
to the provisions of this Article 15, quit and surrender possession of the
Premises to Landlord in as good order and condition as when Tenant took
possession and as thereafter improved by Landlord and/or Tenant, reasonable wear
and tear and repairs which are specifically made the responsibility of Landlord
hereunder excepted.  Upon such expiration or termination, Tenant shall, without
expense to Landlord, remove or cause to be removed from the Premises all
telephone, data, and other cabling and wiring (including any cabling and wiring
associated with the Wi-Fi Network, if any) installed or caused to be installed
by Tenant (including any cabling and wiring, installed above the ceiling of the
Premises or below the floor of the Premises), all debris and rubbish, and such
items of furniture, equipment, free-standing cabinet work, and other articles of
personal property owned by Tenant or installed or placed by Tenant at its
expense in the Premises, and such similar articles of any other persons claiming
under Tenant, as Landlord may, in its sole discretion, require to be removed,
and Tenant shall repair at its own expense all damage to the Premises and
Buildings resulting from such removal.

ARTICLE 16
 
HOLDING OVER
 
If Tenant holds over after the expiration of the Lease Term hereof, with or
without the express or implied consent of Landlord, such tenancy shall be from
month-to-month only, and shall not constitute a renewal hereof or an extension
for any further term, and in such case Base Rent shall be payable at a monthly
rate equal to one hundred fifty percent (150%) of the Base Rent applicable
during the last rental period of the Lease Term under this Lease.  Such
month-to-month tenancy shall be subject to every other term, covenant and
agreement contained herein.  Landlord hereby expressly reserves the right to
require Tenant to surrender possession of the Premises to Landlord as provided
in this Lease upon the expiration or other termination of this Lease.  The
provisions of this Article 16 shall not be deemed to limit or constitute a
waiver of any other rights or remedies of Landlord provided herein or at law. 
If Tenant fails to surrender the Premises upon the termination or expiration of
this Lease, in addition to any other liabilities to Landlord accruing therefrom,
Tenant shall protect, defend, indemnify and hold Landlord harmless from all
loss, costs (including reasonable attorneys' fees) and liability resulting from
such failure, including, without limiting the generality of the foregoing, any
claims made by any succeeding tenant founded upon such failure to surrender, and
any lost profits to Landlord resulting therefrom.
 
ARTICLE 17
 
ESTOPPEL CERTIFICATES
 
Within ten (10) days following a request in writing by Landlord, Tenant shall
execute and deliver to Landlord an estoppel certificate, which, as submitted by
Landlord, shall be in such commercially reasonable form as may be required by
any prospective mortgagee or purchaser of the Project (or any portion thereof),
indicating therein any exceptions thereto that may exist at that time, and shall
also contain any other information reasonably requested by Landlord or
Landlord's Mortgagee or Landlord's prospective mortgagees.  Tenant shall execute
and deliver any other commercially reasonable documents and may be reasonably
required for such purposes.  Failure of Tenant to timely execute and deliver
such estoppel certificate or other documents shall constitute an acceptance of
the Premises and an acknowledgment by Tenant that statements included in the
estoppel certificate are true and correct, without exception.  Failure by Tenant
to so deliver such estoppel certificate shall be a material default of the
provisions of this Lease.  In addition, Tenant shall be liable to Landlord, and
shall indemnify Landlord from and against any loss, cost, damage or expense,
incidental, consequential, or otherwise, including attorneys' fees, arising or
accruing directly or indirectly, from any failure of Tenant to execute or
deliver to Landlord any such estoppel certificate.  Upon request from time to
time, Tenant agrees to provide to Landlord, within ten (10) days after
Landlord's delivery of written request therefor, current financial statements
for Tenant, dated no earlier than one (1) year prior to such written request,
certified as accurate by Tenant or, if available, audited financial statements
prepared by an independent certified public accountant with copies of the
auditor's statement.  If any Guaranty is executed in connection with this Lease,
Tenant also agrees to deliver to Landlord, within ten (10) days after Landlord's
delivery of written request therefor, current financial statements of the
Guarantor in a form consistent with the foregoing criteria.
 

 -18-
MARINA VILLAGE
[Biotime]

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

ARTICLE 18
 
SUBORDINATION
 
This Lease is subject and subordinate to all present and future ground leases of
the Project and to the lien of any mortgages or trust deeds, now or hereafter in
force against the Project, if any, and to all renewals, extensions,
modifications, consolidations and replacements thereof, and to all advances made
or hereafter to be made upon the security of such mortgages or trust deeds,
unless the holders of such mortgages or trust deeds, or the lessors under such
ground lease, require in writing that this Lease be superior thereto. 
Notwithstanding any contrary provision in this Article 18, a condition precedent
to the subordination of this Lease to any future ground or underlying lease or
to the lien of any future mortgage or deed of trust is that Landlord shall
obtain for the benefit of Tenant a commercially reasonable subordination,
non-disturbance and attornment agreement (a "Future SNDA") from the lessor or
beneficiary of such future instrument, acknowledging that the rights and
interests of Tenant under this Lease shall remain in full force and effect and
Tenant's right to possession of the Premises shall not be disturbed during the
Lease Term as long as Tenant is not in default under this Lease beyond all
applicable notice and cure periods.  Tenant covenants and agrees if any
proceedings are brought for the foreclosure of any such mortgage, or if any
ground lease is terminated, to attorn, without any deductions or set-offs
whatsoever, to the purchaser upon any such foreclosure sale, or to the lessor of
such ground lease, as the case may be, if so requested to do so by such
purchaser or lessor, and to recognize such purchaser or lessor as the lessor
under this Lease.  Tenant shall, within five (5) days of request by Landlord,
execute such further instruments or assurances as Landlord may reasonably deem
necessary to evidence or confirm the subordination or superiority of this Lease
to any such mortgages, trust deeds, or ground leases.  Tenant hereby irrevocably
authorizes Landlord to execute and deliver in the name of Tenant any such
instrument or instruments if Tenant fails to do so, provided that such
authorization shall in no way relieve Tenant from the obligation of executing
such instruments of subordination or superiority.  Tenant waives the provisions
of any current or future statute, rule or law which may give or purport to give
Tenant any right or election to terminate or otherwise adversely affect this
Lease and the obligations of the Tenant hereunder in the event of any
foreclosure proceeding or sale.  Landlord shall use commercially reasonable
efforts to cause the beneficiary of the existing deed of trust encumbering the
Project (the "Existing Lender") to execute and deliver to the parties, within
sixty (60) days after execution of this Lease, a commercially reasonable
subordination, non-disturbance and attornment agreement (the "Existing Lender
SNDA"), and Tenant shall execute such Existing Lender SNDA promptly after
request therefor by Landlord.  Landlord's failure to cause the Existing Lender
to execute and deliver to the parties a fully executed Existing Lender SNDA
within such 60-day period or by any other date shall not constitute a default by
Landlord under this Lease, and Tenant shall not be entitled to any remedy under
this Lease, nor shall Landlord be liable to Tenant for any damages or otherwise
due to any such failure by Landlord.  Tenant shall reimburse Landlord for all
out-of-pocket costs actually incurred by Landlord in connection with obtaining
the Existing Lender SNDA within thirty (30) days after Tenant's receipt of
Landlord's invoice therefor.
 
ARTICLE 19
 
TENANT'S DEFAULTS; LANDLORD'S REMEDIES
 
19.1        Events of Default by Tenant.  All covenants and agreements to be
kept or performed by Tenant under this Lease shall be performed by Tenant at
Tenant's sole cost and expense and without any reduction of Rent.  The
occurrence of any of the following shall constitute a default of this Lease by
Tenant:
 
19.1.1         Any failure by Tenant to pay any Rent or any other charge
required to be paid under this Lease, or any part thereof, within five (5) days
after written notice of delinquency is delivered to Tenant by Landlord;
provided, however, that if Landlord has given Tenant one (1) such delinquency
notice in the preceding twelve (12) consecutive month period, then Tenant's
subsequent failure to pay any Rent or other charge when due shall constitute a
default under this Lease without requirement of any notice or cure period;
provided, further, that any such delinquency notice shall be in lieu of, and not
in addition to, any notice required under California Code of Civil Procedure
Section 1161 or any similar or successor law; or
 
19.1.2         Any failure by Tenant to observe or perform any other provision,
covenant or condition of this Lease to be observed or performed by Tenant where
such failure continues for thirty (30) days after written notice thereof from
Landlord to Tenant; provided however, that any such notice shall be in lieu of,
and not in addition to, any notice required under California Code of Civil
Procedure Section 1161 or any similar or successor law; and provided further
that if the nature of such default is such that the same cannot reasonably be
cured within a thirty (30)-day period, Tenant shall not be deemed to be in
default if it diligently commences such cure within such period and thereafter
diligently proceeds to rectify and cure said default as soon as possible; or
 
19.1.3         Abandonment of the Premises by Tenant other than in connection
with any damage to or destruction of the Premises or any condemnation or other
action of any governmental agency or authority prohibiting the use or occupation
of the Premises or the Buildings.
 

 -19-
MARINA VILLAGE
[Biotime]

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

19.2        Landlord's Remedies Upon Default.  Upon the occurrence of any such
default by Tenant, Landlord shall have, in addition to any other remedies
available to Landlord at law or in equity, the option to pursue any one or more
of the following remedies, each and all of which shall be cumulative and
nonexclusive, without any notice or demand whatsoever.
 
19.2.1         Terminate this Lease, in which event Tenant shall immediately
surrender the Premises to Landlord, and if Tenant fails to do so, Landlord may,
without prejudice to any other remedy which it may have for possession or
arrearages in rent, enter upon and take possession of the Premises and expel or
remove Tenant and any other person who may be occupying the Premises or any part
thereof, without being liable for prosecution or any claim or damages therefor;
and Landlord may recover from Tenant the following:
 
(i)                  the worth at the time of award of any unpaid rent which has
been earned at the time of such termination; plus
 
(ii)                the worth at the time of award of the amount by which the
unpaid rent which would have been earned after termination until the time of
award exceeds the amount of such rental loss that Tenant proves could have been
reasonably avoided; plus
 
(iii)               the worth at the time of award of the amount by which the
unpaid rent for the balance of the Lease Term after the time of award exceeds
the amount of such rental loss that Tenant proves could have been reasonably
avoided; plus
 
(iv)              any other amount necessary to compensate Landlord for all the
detriment proximately caused by Tenant's failure to perform its obligations
under this Lease or which in the ordinary course of things would be likely to
result therefrom, specifically including but not limited to, brokerage
commissions and advertising expenses incurred, expenses of remodeling the
Premises or any portion thereof for a new tenant, whether for the same or a
different use, and any special concessions made to obtain a new tenant; plus
 
(v)                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
Laws.
 
The term "rent" as used in this Section 19.2 shall be deemed to be and to mean
all sums of every nature required to be paid by Tenant pursuant to the terms of
this Lease, whether to Landlord or to others.  As used in Sections 19.2.1(i) and
(ii), above, the "worth at the time of award" shall be computed by allowing
interest at the Interest Rate set forth in Section 4.5 above.  As used in
Section 19.2.1(iii) above, the "worth at the time of award" shall be computed by
discounting such amount at the discount rate of the Federal Reserve Bank of San
Francisco at the time of award plus one percent (1%).
 
19.2.2         Landlord shall have the remedy described in California Civil Code
Section 1951.4 (lessor may continue lease in effect after lessee's breach and
abandonment and recover rent as it becomes due, if lessee has the right to
sublet or assign, subject only to reasonable limitations).  Accordingly, if
Landlord does not elect to terminate this Lease on account of any default by
Tenant, Landlord may, from time to time, without terminating this Lease, enforce
all of its rights and remedies under this Lease, including the right to recover
all rent as it becomes due.
 
19.2.3         Landlord may, but shall not be obligated to, make any such
payment or perform or otherwise cure any such obligation, provision, covenant or
condition on Tenant's part to be observed or performed (and may enter the
Premises for such purposes).  In the event of Tenant's failure to perform any of
its obligations or covenants under this Lease, and such failure to perform poses
a material risk of injury or harm to persons or damage to or loss of property,
then Landlord shall have the right to cure or otherwise perform such covenant or
obligation at any time after such failure to perform by Tenant, whether or not
any such notice or cure period set forth in Section 19.1 above has expired.  Any
such actions undertaken by Landlord pursuant to the foregoing provisions of this
Section 19.2.3 shall not be deemed a waiver of Landlord's rights and remedies as
a result of Tenant's failure to perform and shall not release Tenant from any of
its obligations under this Lease.
 
19.3        Payment by Tenant.  Tenant shall pay to Landlord, within ten (10)
days after delivery by Landlord to Tenant of statements therefor:  (i) sums
equal to expenditures reasonably made and obligations incurred by Landlord in
connection with Landlord's performance or cure of any of Tenant's obligations
pursuant to the provisions of Section 19.2.3 above; and (ii) sums equal to all
expenditures made and obligations incurred by Landlord in collecting or
attempting to collect the Rent or in enforcing or attempting to enforce any
rights of Landlord under this Lease or pursuant to law, including, without
limitation, all legal fees and other amounts so expended.  Tenant's obligations
under this Section 19.3 shall survive the expiration or sooner termination of
the Lease Term.
 
19.4        Sublessees of Tenant.  Whether or not Landlord elects to terminate
this Lease on account of any default by Tenant, as set forth in this Article 19,
Landlord shall have the right to terminate any and all subleases, licenses,
concessions or other consensual arrangements for possession entered into by
Tenant and affecting the Premises or may, in Landlord's sole discretion, succeed
to Tenant's interest in such subleases, licenses, concessions or arrangements. 
If Landlord elects to succeed to Tenant's interest in any such subleases,
licenses, concessions or arrangements, Tenant shall, as of the date of notice by
Landlord of such election, have no further right to or interest in the rent or
other consideration receivable thereunder.
 
19.5        Waiver of Default.  No waiver by Landlord of any violation or breach
by Tenant of any of the terms, provisions and covenants herein contained shall
be deemed or construed to constitute a waiver of any other or later violation or
breach by Tenant of the same or any other of the terms, provisions, and
covenants herein contained.  Forbearance by Landlord in enforcement of one or
more of the remedies herein provided upon a default by Tenant shall not be
deemed or construed to constitute a waiver of such default.  The acceptance of
any Rent hereunder by Landlord following the occurrence of any default, whether
or not known to Landlord, shall not be deemed a waiver of any such default,
except only a default in the payment of the Rent so accepted.
 

 -20-
MARINA VILLAGE
[Biotime]

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

19.6        Efforts to Relet.  For the purposes of this Article 19, Tenant's
right to possession shall not be deemed to have been terminated by efforts of
Landlord to relet the Premises, by its acts of maintenance or preservation with
respect to the Premises, or by appointment of a receiver to protect Landlord's
interests hereunder.  The foregoing enumeration is not exhaustive, but merely
illustrative of acts which may be performed by Landlord without terminating
Tenant's right to possession.
 
ARTICLE 20
 
SECURITY DEPOSIT
 
Concurrent with Tenant's execution of this Lease, Tenant shall deposit with
Landlord a security deposit (the "Security Deposit") in the amount set forth in
Section 10 of the Summary.  The Security Deposit shall be held by Landlord as
security for the faithful performance by Tenant of all the terms, covenants, and
conditions of this Lease to be kept and performed by Tenant during the Lease
Term.  If Tenant defaults with respect to any provisions of this Lease,
including, but not limited to, the provisions relating to the payment of Rent,
Landlord may, but shall not be required to, use, apply or retain all or any part
of the Security Deposit for the payment of any Rent or any other sum in default,
or for the payment of any amount that Landlord may spend or become obligated to
spend by reason of Tenant's default, or to compensate Landlord for any other
loss or damage that Landlord may suffer by reason of Tenant's default.  If any
portion of the Security Deposit is so used or applied, Tenant shall, within five
(5) business days after written demand therefor, deposit cash with Landlord in
an amount sufficient to restore the Security Deposit to its original amount, and
Tenant's failure to do so shall be a default under this Lease.  If Tenant shall
fully and faithfully perform every provision of this Lease to be performed by
it, the Security Deposit, or any balance thereof, shall be returned to Tenant,
or, at Landlord's option, to the last assignee of Tenant's interest hereunder,
within sixty (60) days following the expiration of the Lease Term.  Tenant shall
not be entitled to any interest on the Security Deposit.  Tenant hereby waives
the provisions of Section 1950.7 of the California Civil Code, and all other
provisions of law, now or hereafter in force, which provide that Landlord may
claim from a security deposit only those sums reasonably necessary to remedy
defaults in the payment of rent, to repair damage caused by Tenant or to clean
the Premises, it being agreed that Landlord may, in addition, claim those sums
reasonably necessary to compensate Landlord for any other loss or damage,
foreseeable or unforeseeable, caused by the act or omission of Tenant or any
officer, employee, agent or invitee of Tenant.  Notwithstanding the foregoing,
and provided Tenant is not in default under this Lease as of the First Security
Deposit Reduction Date or the Second Security Deposit Reduction Date as defined
and set forth hereinbelow (as the case may be), Landlord shall reduce the
Security Deposit held by Landlord by (i) Four Hundred Twenty-Three Thousand Four
Hundred Thirty-One and 25/100 Dollars ($423,431.25) (the "First Security Deposit
Reduction Amount") on the first (1st) day of the twenty-fifth (25th) month of
the initial Lease Term (the "First Security Deposit Reduction Date"), and (ii)
Three Hundred Forty-Six Thousand One Hundred Thirty-Five and 80/100 Dollars
($346,135.80) (the "Second Security Deposit Reduction Amount") on the first
(1st) day of the thirty-seventh (37th) month of the initial Lease Term (the
"Second Security Deposit Reduction Date").  Landlord shall apply (A) the First
Security Deposit Reduction Amount as a credit against the monthly installment(s)
of Base Rent first due and payable by Tenant under this Lease following the
First Security Deposit Reduction Date, and (B) the Second Security Deposit
Reduction Amount as a credit against the monthly installment(s) of Base Rent
first due and payable by Tenant under this Lease following the Second Security
Deposit Reduction Date.  Notwithstanding anything to the contrary contained
herein, and provided Tenant is not in default under this Lease following any
applicable notice and cure periods, Tenant shall have the right, at any time
during the Lease Term, to deliver to Landlord an irrevocable and unconditional
negotiable letter of credit in a form approved by Landlord, in Landlord's sole
discretion (the "Letter of Credit") in the amount of the then-existing Security
Deposit held by Landlord, subject, however, to the condition precedent that
Tenant execute and deliver to Landlord the Landlord's standard form letter of
credit agreement (which provides, among other things, that (A) if Tenant
defaults under this Lease beyond any applicable notice and cure periods,
Landlord may, but without obligation to do so, draw upon the Letter of Credit in
part or in whole, to cure any such default and/or to compensate Landlord for any
and all damages of any kind or nature sustained or which Landlord reasonably
estimates that it will sustain resulting from such default, and (B) Tenant shall
not interfere in any way with payment to Landlord of the proceeds of the Letter
of Credit, either prior to or following a draw by Landlord of any portion of the
Letter of Credit).  Any such Letter of Credit must be:  (1) payable in the
county in which the Building is located, name Landlord as beneficiary, and be
issued by a solvent nationally recognized bank that is acceptable to Landlord in
Landlord's sole discretion; (2) maintained in effect, whether through renewal or
extension, until the date which is one hundred twenty (120) days after the
expiration of the Lease Term; and (3) fully assignable by Landlord, and permit
partial draws.  If and to the extent Tenant delivers such Letter of Credit to
Landlord prior to the first (1st) day of the thirty-seventh (37th) month of the
initial Lease Term, such Letter of Credit shall contain a reduction schedule
consistent with the reduction schedule set forth in the clauses (i) and (ii)
hereinabove.  Within ten (10) business days following Landlord's receipt of the
Letter of Credit and such executed letter of credit agreement, Landlord shall
return the Security Deposit to Tenant.
 

 -21-
MARINA VILLAGE
[Biotime]

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

ARTICLE 21
 
COMPLIANCE WITH LAW
 
Tenant shall not do anything or suffer anything to be done in or about the
Premises which will in any way conflict with any law, statute, ordinance or
other governmental rule, regulation or requirement now in force or which may
hereafter be enacted or promulgated (collectively, "Applicable Laws").  At its
sole cost and expense, Tenant shall promptly comply with all Applicable Laws
pertaining to the Premises and/or Tenant's use of and/or activities in the
Premises and the Project, subject to Landlord's obligation as set forth
hereinbelow to comply with Applicable Laws with respect to those portions of the
Buildings and Project that are Landlord's responsibility to maintain and repair
pursuant to Section 7.2 above.  In addition, Tenant shall fully comply with all
present or future government-mandated programs intended to manage parking,
transportation or traffic in and around the Project, and in connection
therewith, Tenant shall take responsible action for the transportation planning
and management of all employees located at the Premises by working directly with
Landlord, any governmental transportation management organization or any other
transportation-related committees or entities.  Notwithstanding the foregoing
provisions of this Article 21 to the contrary, Landlord shall comply with all
Applicable Laws relating to those portions of the Buildings and Project that are
Landlord's responsibility to repair and maintain pursuant to Section 7.2 above;
provided, however, to the extent Landlord's compliance obligations are triggered
by any improvements or Alterations made to the Premises by or on behalf of
Tenant (including the initial Tenant Improvements described in the Tenant Work
Letter), any trade fixtures, furniture, equipment or personal property installed
by Tenant in the Premises, and/or Tenant's particular manner of use of the
Premises, Tenant shall reimburse Landlord for the cost of such compliance within
thirty (30) days after invoice therefor from Landlord.  For purposes of Section
1938 of the California Civil Code, Landlord hereby discloses to Tenant, and
Tenant hereby acknowledges, that the Premises have not undergone inspection by a
Certified Access Specialist (CASp).
 
ARTICLE 22
 
ENTRY BY LANDLORD
 
Landlord reserves the right at all reasonable times and upon not less than two
(2) business days' prior notice (except no such prior notice shall be required
in case of emergency) to Tenant to enter the Premises to:  (i) inspect them;
(ii) show the Premises to prospective purchasers, mortgagees or tenants, or to
the ground lessors; or (iii) to post notices of nonresponsibility.   Upon not
less than three (3) business days' prior notice to Tenant (except no such prior
notice shall be required in case of emergency), Landlord may enter the Premises
to alter, improve or repair the Premises or the Buildings if necessary to comply
with current building codes or other Applicable Laws, or for structural
alterations, repairs or improvements to the Buildings.  Notwithstanding anything
to the contrary contained in this Article 22, Landlord may enter the Premises at
any time, without notice to Tenant, in emergency situations and/or to perform
other services required of Landlord pursuant to this Lease.  In exercising any
rights of entry to the Premises, Landlord shall make commercially reasonable
efforts to not unreasonably interfere with or disrupt the normal operation of
Tenant's business (except in the case of emergency).  Any such entries shall be
without the abatement of Rent and shall include the right to take such
reasonable steps as required to accomplish the stated purposes.  Except as
provided in Section 6.6 above, Tenant hereby waives any claims for damages or
for any injuries or inconvenience to or interference with Tenant's business,
lost profits, any loss of occupancy or quiet enjoyment of the Premises, and any
other loss occasioned thereby.  For each of the above purposes, Landlord shall
at all times have a key with which to unlock all the doors in the Premises,
excluding Tenant's vaults, safes and special security areas designated in
advance by Tenant.  In an emergency, Landlord shall have the right to enter
without notice and use any means that Landlord may deem proper to open the doors
in and to the Premises.  Any entry into the Premises in the manner hereinbefore
described shall not be deemed to be a forcible or unlawful entry into, or a
detainer of, the Premises, or an actual or constructive eviction of Tenant from
any portion of the Premises.
 
ARTICLE 23
 
PARKING
 
Throughout the Lease Term, Tenant shall have the right to use, on a "first-come,
first-serve" basis, in common with other tenants of the Buildings and free of
parking charges, the number of unreserved parking spaces set forth in Section 12
of the Summary, which unreserved parking spaces are located in those Parking
Facilities servicing the applicable Building as shall be designated by Landlord
from time to time for unreserved parking for the tenants of such applicable
Building.  Tenant's continued right to use the parking spaces is conditioned
upon (i) Tenant abiding by (A) the Parking Rules and Regulations which are in
effect on the date hereof, as set forth in the attached Exhibit D and all
reasonable and non-discriminatory modifications and additions thereto that are
not inconsistent with Tenant's rights under this Lease, which are prescribed
from time to time for the orderly operation and use of the Parking Facilities by
Landlord, and/or Landlord's Parking Operator (as defined below), (B) all rules
and regulations which are prescribed from time to time by any common area
association of the Project having rights over the Parking Facilities, and (C)
all recorded covenants, conditions and restrictions affecting the Buildings
and/or the Project, and (ii) upon Tenant's cooperation in seeing that Tenant's
employees and visitors also comply with the Parking Rules and Regulations (and
all such modifications and additions thereto, as the case may be), any such
other rules and regulations and covenants, conditions and restrictions. 
Landlord (and/or any other owners of Marina Village) specifically reserve the
right to change the size, configuration, design, layout, location and all other
aspects of the Parking Facilities, and Tenant acknowledges and agrees that
Landlord may, without incurring any liability to Tenant and without any
abatement of Rent under this Lease, from time to time, temporarily close-off or
restrict access to any or all of the Parking Facilities; provided, however, that
such actions shall not result in a permanent reduction in the number of
unreserved parking spaces that Tenant has the right to use under this Lease as
set forth in Section 12 of the Summary.  Landlord may delegate its
responsibilities hereunder to a parking operator (the "Parking Operator") in
which case the Parking Operator shall have all the rights of control attributed
hereby to Landlord.  The parking rights provided to Tenant pursuant to this
Article 23 are provided solely for use by Tenant's own personnel and such rights
may not be transferred, assigned, subleased or otherwise alienated by Tenant
without Landlord's prior approval, except in connection with an assignment of
this Lease or sublease of the Premises made in accordance with Article 14
above.  All visitor parking by Tenant's visitors shall be subject to
availability, as reasonably determined by Landlord (and/or the Parking Operator,
as the case may be), parking in such visitor parking areas as may be designated
by Landlord (and/or the Parking Operator and/or any common area association of
the Project having rights over the Parking Facilities) from time to time.
 

 -22-
MARINA VILLAGE
[Biotime]

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

ARTICLE 24
 
MISCELLANEOUS PROVISIONS
 
24.1        Terms; Captions.  The necessary grammatical changes required to make
the provisions hereof apply either to corporations or partnerships or
individuals, men or women, as the case may require, shall in all cases be
assumed as though in each case fully expressed.  The captions of Articles and
Sections are for convenience only and shall not be deemed to limit, construe,
affect or alter the meaning of such Articles and Sections.
 
24.2        Binding Effect.  Each of the provisions of this Lease shall extend
to and shall, as the case may require, bind or inure to the benefit not only of
Landlord and of Tenant, but also of their respective successors or assigns,
provided this clause shall not permit any assignment by Tenant contrary to the
provisions of Article 14 above.
 
24.3        No Waiver.  No waiver of any provision of this Lease shall be
implied by any failure of a party to enforce any remedy on account of the
violation of such provision, even if such violation shall continue or be
repeated subsequently, any waiver by a party of any provision of this Lease may
only be in writing, and no express waiver shall affect any provision other than
the one specified in such waiver and that one only for the time and in the
manner specifically stated.  No receipt of monies by Landlord from Tenant after
the termination of this Lease shall in any way alter the length of the Lease
Term or of Tenant's right of possession hereunder or after the giving of any
notice shall reinstate, continue or extend the Lease Term or affect any notice
given Tenant prior to the receipt of such monies, it being agreed that after the
service of notice or the commencement of a suit or after final judgment for
possession of the Premises, Landlord may receive and collect any Rent due, and
the payment of said Rent shall not waive or affect said notice, suit or
judgment.
 
24.4        Modification of Lease.  If any current or prospective mortgagee or
ground lessor for the Project requires modifications to this Lease, which
modifications will not cause an increased cost or expense to Tenant or in any
other way materially and adversely change the rights and obligations of Tenant
hereunder, then and in such event, Tenant agrees that this Lease may be so
modified and agrees to execute whatever documents are required therefor and
deliver the same to Landlord within ten (10) days following the request
therefor.  If Landlord or any such current or prospective mortgagee or ground
lessor require execution of a short form of Lease for recording, containing,
among other customary provisions, the names of the parties, a description of the
Premises and the Lease Term, Tenant shall execute such short form of Lease and
to deliver the same to Landlord within ten (10) days following the request
therefor.
 
24.5        Transfer of Landlord's Interest.  Landlord has the right to transfer
all or any portion of its interest in the Project, the Buildings and/or in this
Lease, and upon any such transfer, Landlord shall automatically be released from
all liability under this Lease arising after the effective date of such transfer
and Tenant shall look solely to such transferee for the performance of
Landlord's obligations hereunder arising after the date of such transfer
provided such transferee assumes in writing the obligations of Landlord under
this Lease arising after the effective date of such transfer.  The liability of
any transferee of Landlord shall be limited to the interest of such transferee
in the Project.  Landlord may also assign its interest in this Lease to a
mortgage lender as additional security but such assignment shall not release
Landlord from its obligations hereunder and Tenant shall continue to look to
Landlord for the performance of its obligations hereunder.
 
24.6        Prohibition Against Recording.  Except as provided in Section 24.4
of this Lease, neither this Lease, nor any memorandum, affidavit or other
writing with respect thereto, shall be recorded by Tenant or by anyone acting
through, under or on behalf of Tenant, and the recording thereof in violation of
this provision shall make this Lease null and void at Landlord's election.
 
24.7        Landlord's Title; Air Rights.  Landlord's title is and always shall
be paramount to the title of Tenant.  Nothing herein contained shall empower
Tenant to do any act which can, shall or may encumber the title of Landlord.  No
rights to any view or to light or air over any property, whether belonging to
Landlord or any other person, are granted to Tenant by this Lease.
 

 -23-
MARINA VILLAGE
[Biotime]

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

24.8        Tenant's Signs.
 
24.8.1        Signage Monuments. Subject to the approval of all applicable
governmental entities, and subject to all Applicable Laws, Landlord hereby
grants Tenant the right to have Tenant's name "BioTime" and the name of other
Business Affiliates (provided the names of such Business Affiliates fit within
the space allotted to Tenant on the Signage Monument), but no other markings,
displayed on (i) the existing monument sign for the 1010 Building located at the
front entrance to the 1010 Building (the "1010 Signage Monument"), and (ii) the
existing monument sign for the 1020 Building located at the front entrance to
the 1020 Building (the "1020 Signage Monument", and together with the 1010
Signage Monument, collectively, the "Signage Monuments"). The design, size,
specifications, graphics, materials, colors and exact location with respect to
Tenant's name on each of the Signage Monuments shall be (A) consistent with the
quality and appearance of the Buildings and Project, and (B) designated by
Landlord, subject to the approval of all applicable governmental authorities.
Landlord shall install Tenant's name on each of the Signage Monuments at
Landlord's expense. Tenant shall pay to Landlord, within ten (10) days after
demand, from time to time, all costs attributable to the insurance, maintenance
and repair of Tenant's name on each Signage Monument, plus a pro-rata share of
the costs of maintenance, insurance, and repair of each Signage Monument (such
pro-rata share for each applicable Signage Monument to be determined by Landlord
based upon the number of tenant signs on such applicable Signage Monument).
Landlord shall have the right to relocate, redesign and/or reconstruct the
Signage Monuments from time to time. The rights granted to Tenant under this
Section 24.8.1 (1) are personal to (v) the original Tenant executing this Lease
(the "Original Tenant"), (w) to any Affiliate to which the Original Tenant
assigns its entire interest in this Lease pursuant to Section 14.7 above (each,
an "Affiliate Assignee") or any Business Affiliate, (x) any non-Affiliate
Transferee of Tenant's entire interest under this Lease pursuant to Article 14
above (a "Non-Affiliate Assignee"), (y) with respect to Tenant's sign on the
1010 Signage Monument, any Transferee to whom Tenant has assigned such signage
rights who subleases the entire rentable square feet of the 1010 Premises for
the remainder of the Lease Term, or (z) with respect to Tenant's sign on the
1020 Signage Monument, any Transferee to whom Tenant has assigned such signage
rights who subleases the entire rentable square feet of the 1020 Premises for
the remainder of the Lease Term (such subtenant Transferees to whom such
applicable signage rights have been assigned as described in clauses (y) and (z)
hereinabove are collectively referred to herein as "Major Subtenants"), (but any
name change on the Signage Monuments to reflect the name of such Affiliate
Assignee, such Business Affiliate, such Non-Affiliate Assignee or such
applicable Major Subtenants (as the case may be) shall be subject to Landlord's
prior reasonable approval), (2) may not be assigned or exercised by or to, or
used by, any other person or entity other than the Original Tenant, such
Affiliate Assignee, such Business Affiliate, such Non-Affiliate Assignee or such
applicable Major Subtenants, as the case may be, and (3) shall only be available
to and exercisable by the Original Tenant, such Affiliate Assignee, such
Business Affiliate, such Non-Affiliate Assignee or such applicable Major
Subtenants, as the case may be, when the Original Tenant, such Affiliate
Assignee, such Business Affiliate, such Non-Affiliate Assignee or such
applicable Major Subtenants, as the case may be, is in actual and physical
possession of the entire Premises (except that with respect to Tenant's sign on
the 1010 Signage Monument and Tenant's sign on the 1020 Signage Monument,
respectively, shall only be available to and exercised by the Original Tenant,
the Affiliate Assignee, the Business Affiliate, the Non-Affiliate Assignee or
the applicable Major Subtenant to which such applicable signs have been assigned
when the Original Tenant, the Affiliate Assignee, the Business Affiliate, the
Non-Affiliate Assignee or such applicable Major Subtenant is an actual and
physical possession of the entire rentable square feet of the 1010 Premises
[with respect to the 1010 Signage Monument] or the 1020 Premises [with respect
to the 1020 Signage Monument], respectively, as the case may be). Upon
termination or expiration of this Lease, or upon the earlier termination of
Tenant's rights under this Section 24.8.1, Landlord shall have the right to
permanently remove Tenant's name from the Signage Monuments and to restore and
repair all damage to the Signage Monuments resulting from such removal, and
Tenant shall pay to Landlord, within ten (10) days after demand, all costs
incurred in connection with such removal, restoration and repair.
 
24.8.2         Identification Signs.  Tenant shall be entitled, at its sole cost
and expense, to (i) one (1) identification sign on or near the entry doors of
the 1010 Premises, and (ii) one (1) identification sign on or near the entry
doors of the 1020 Premises (collectively, the "Identification Signs").  The
Identification Signs shall be installed by a signage contractor designated by
Landlord.  The location, quality, design, style and size of the Identification
Signs shall be consistent with the Landlord's Building standard signage program
and shall be subject to Landlord's prior written approval, in its reasonable
discretion; provided, however, that the Identification Signs may show the name
of Tenant, any Affiliate Assignee, any Business Affiliate, any Non-Affiliate
Assignee or any applicable Major Subtenants (as the case may be).
 
24.8.3         No Other Signs.  Except for the Identification Signs and Tenant's
(or any Affiliate Assignee's, Business Affiliate's, any Non-Affiliate Assignee's
or any applicable Major Subtenant's [as the case may be]) name on the Signage
Monuments, Tenant may not install any signs on the exterior or roof of the
Buildings, the Other Existing Buildings or the common areas of the Buildings or
the Project.  Any signs, window coverings, or blinds, or other items visible
from the exterior of the Premises or Buildings are subject to the prior approval
of Landlord, in its sole and absolute discretion.
 
24.9        Relationship of Parties.  Nothing contained in this Lease shall be
deemed or construed by the parties hereto or by any third party to create the
relationship of principal and agent, partnership, joint venturer or any
association between Landlord and Tenant, it being expressly understood and
agreed that neither the method of computation of Rent nor any act of the parties
hereto shall be deemed to create any relationship between Landlord and Tenant
other than the relationship of landlord and tenant.
 
24.10     Application of Payments.  Landlord shall have the right to apply
payments received from Tenant pursuant to this Lease, regardless of Tenant's
designation of such payments, to satisfy any obligations of Tenant hereunder, in
such order and amounts as Landlord, in its sole discretion, may elect.
 
24.11    Time of Essence.  Time is of the essence of this Lease and each of its
provisions.
 
24.12     Partial Invalidity.  If any term, provision or condition contained in
this Lease shall, to any extent, be invalid or unenforceable, the remainder of
this Lease, or the application of such term, provision or condition to persons
or circumstances other than those with respect to which it is invalid or
unenforceable, shall not be affected thereby, and each and every other term,
provision and condition of this Lease shall be valid and enforceable to the
fullest extent possible permitted by law.
 
24.13     No Warranty.  In executing and delivering this Lease, Tenant has not
relied on any representation, including, but not limited to, any representation
whatsoever as to the amount of any item comprising Additional Rent or the amount
of the Additional Rent in the aggregate or that Landlord is furnishing the same
services to other tenants, at all, on the same level or on the same basis, or
any warranty or any statement of Landlord which is not set forth herein or in
one or more of the Exhibits attached hereto.
 

 -24-
MARINA VILLAGE
[Biotime]

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

24.14   Landlord Exculpation. Notwithstanding anything in this Lease to the
contrary, and notwithstanding any Applicable Law to the contrary, the liability
of Landlord and the Landlord Parties under this Lease (including any successor
landlord) and any recourse by Tenant against Landlord or the Landlord Parties
shall be limited solely and exclusively to an amount which is equal to the
ownership interest of Landlord in the Project (including any rental, insurance
and condemnation proceeds therefrom), and neither Landlord, nor any of the
Landlord Parties shall have any personal liability therefor, and Tenant hereby
expressly waives and releases such personal liability on behalf of itself and
all persons claiming by, through or under Tenant.
 
24.15     Entire Agreement.  There are no oral agreements between the parties
hereto affecting this Lease and this Lease supersedes and cancels any and all
previous negotiations, arrangements, brochures, agreements and understandings,
if any, between the parties hereto or displayed by Landlord to Tenant with
respect to the subject matter thereof, and none thereof shall be used to
interpret or construe this Lease.  This Lease and any side letter or separate
agreement executed by Landlord and Tenant in connection with this Lease and
dated of even date herewith contain all of the terms, covenants, conditions,
warranties and agreements of the parties relating in any manner to the rental,
use and occupancy of the Premises, shall be considered to be the only agreement
between the parties hereto and their representatives and agents, and none of the
terms, covenants, conditions or provisions of this Lease can be modified,
deleted or added to except in writing signed by the parties hereto.  All
negotiations and oral agreements acceptable to both parties have been merged
into and are included herein.  There are no other representations or warranties
between the parties, and all reliance with respect to representations is based
totally upon the representations and agreements contained in this Lease.
 
24.16     Right to Lease.  Landlord reserves the absolute right to effect such
other tenancies in the Buildings, the Other Existing Buildings and/or in any
other building and/or any other portion of the Project as Landlord in the
exercise of its sole business judgment shall determine to best promote the
interests of the Project.  Tenant does not rely on the fact, nor does Landlord
represent, that any specific tenant or type or number of tenants shall, during
the Lease Term, occupy any space in the Buildings, the Other Existing Buildings
or Project.
 
24.17     Force Majeure.  Any prevention, delay or stoppage due to strikes,
labor lockouts by third (3rd) party vendors, labor disputes, acts of God,
inability to obtain services, labor, or materials or reasonable substitutes
therefor, governmental actions, civil commotions, fire or other casualty, and
other causes beyond the reasonable control of the party obligated to perform,
except with respect to the obligations imposed with regard to Rent and other
charges to be paid by Tenant pursuant to this Lease and except with respect to
Tenant's obligations under the Tenant Work Letter (collectively, the "Force
Majeure"), notwithstanding anything to the contrary contained in this Lease,
shall excuse the performance of such party for a period equal to any such
prevention, delay or stoppage and, therefore, if this Lease specifies a time
period for performance of an obligation of either party, that time period shall
be extended by the period of any delay in such party's performance caused by a
Force Majeure.
 
24.18     Waiver of Redemption by Tenant.  Tenant hereby waives for Tenant and
for all those claiming under Tenant all right now or hereafter existing to
redeem by order or judgment of any court or by any legal process or writ,
Tenant's right of occupancy of the Premises after any termination of this Lease.
 
24.19    Notices.  All notices, demands, statements or communications
(collectively, "Notices") given or required to be given by either party to the
other hereunder shall be in writing, shall be sent by United States certified or
registered mail, postage prepaid, return receipt requested, or by nationally
recognized overnight courier using next business day service, or delivered
personally (i) to Tenant at the appropriate address set forth in Section 5 of
the Summary, or to such other place as Tenant may from time to time designate in
a Notice to Landlord; or (ii) to Landlord at the addresses set forth in Section
3 of the Summary, or to such other firm or to such other place as Landlord may
from time to time designate in a Notice to Tenant.  Any Notice will be deemed
given four (4) days after it is sent by United States mail, one (1) business day
after it is sent by nationally recognized overnight courier using next business
day service  or upon the date personal delivery is made or rejected.  If Tenant
is notified of the identity and address of Landlord's mortgagee or ground
lessor, Tenant shall give to such mortgagee or ground lessor written notice of
any default by Landlord under the terms of this Lease by registered or certified
mail, and such mortgagee or ground lessor shall be given a reasonable
opportunity to cure such default prior to Tenant's exercising any remedy
available to Tenant.
 
24.20     Joint and Several.  If there is more than one person or entity
executing this Lease as Tenant, the obligations imposed upon such persons and
entities under this Lease are and shall be joint and several.
 
24.21     Authority.  Each individual executing this Lease on behalf of Tenant
hereby represents and warrants that Tenant is a duly formed and existing entity
qualified to do business in the state in which the Project is located and that
Tenant has full right and authority to execute and deliver this Lease and that
each person signing on behalf of Tenant is authorized to do so.  Tenant confirms
that it is not in violation of any executive order or similar governmental
regulation or law, which prohibits terrorism or transactions with suspected or
confirmed terrorists or terrorist entities or with persons or organizations that
are associated with, or that provide any form of support to, terrorists.  Tenant
further confirms that it will comply throughout the Term of this Lease, with all
governmental laws, rules or regulations governing transactions or business
dealings with any suspected or confirmed terrorists or terrorist entities, as
identified from time to time by the U.S. Treasury Department's Office of Foreign
Assets Control or any other applicable governmental entity.
 
24.22     Jury Trial; Attorneys' Fees.  IF EITHER PARTY COMMENCES LITIGATION
AGAINST THE OTHER FOR THE SPECIFIC PERFORMANCE OF THIS LEASE, FOR DAMAGES FOR
THE BREACH HEREOF OR OTHERWISE FOR ENFORCEMENT OF ANY REMEDY HEREUNDER, THE
PARTIES HERETO AGREE TO AND HEREBY DO WAIVE ANY RIGHT TO A TRIAL BY JURY.  In
the event of any such commencement of litigation, the prevailing party shall be
entitled to recover from the other party such costs and reasonable attorneys'
fees as may have been incurred, including any and all costs incurred in
enforcing, perfecting and executing such judgment.
 

 -25-
MARINA VILLAGE
[Biotime]

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

24.23     Governing Law.  This Lease shall be construed and enforced in
accordance with the laws of the state in which the Project is located.
 
24.24     Submission of Lease.  Submission of this instrument for examination or
signature by Tenant does not constitute a reservation of or an option for lease,
and it is not effective as a lease or otherwise until execution and delivery by
both Landlord and Tenant.
 
24.25     Brokers.  Landlord and Tenant each hereby represents and warrants to
the other party that it (i) has had no dealings with any real estate broker or
agent in connection with the negotiation of this Lease, excepting only the real
estate brokers or agents specified in Section 11 of the Summary (collectively,
the "Brokers"), and (ii) knows of no other real estate broker or agent who is
entitled to a commission in connection with this Lease.  Each party agrees to
indemnify and defend the other party against and hold the other party harmless
from any and all claims, demands, losses, liabilities, lawsuits, judgments, and
costs and expenses (including without limitation reasonable attorneys' fees)
with respect to any leasing commission or equivalent compensation alleged to be
owing on account of the indemnifying party's dealings with any real estate
broker or agent in connection with this Lease other than the Brokers.
 
24.26     Independent Covenants.  This Lease shall be construed as though the
covenants herein between Landlord and Tenant are independent and not dependent
and Tenant hereby expressly waives the benefit of any statute to the contrary
and agrees that if Landlord fails to perform its obligations set forth herein,
Tenant shall not be entitled to make any repairs or perform any acts hereunder
at Landlord's expense or to any setoff of the Rent or other amounts owing
hereunder against Landlord; provided, however, that the foregoing shall in no
way impair the right of Tenant to commence a separate action against Landlord
for any violation by Landlord of the provisions hereof so long as notice is
first given to Landlord and any holder of a mortgage or deed of trust covering
the Buildings, Project or any portion thereof, of whose address Tenant has
theretofore been notified, and an opportunity is granted to Landlord and such
holder to correct such violations as provided above.
 
24.27     Building Name and Signage.  Landlord shall have the right at any time
to change the name(s) of the Building, the Other Existing Buildings and Project
and to install, affix and maintain any and all signs on the exterior and on the
interior of the Buildings, the Other Existing Buildings and any portion of the
Project as Landlord may, in Landlord's sole discretion, desire.  Tenant shall
not use the names of the Buildings, the Other Existing Buildings or Project or
use pictures or illustrations of the Buildings, the Other Existing Buildings or
Project in advertising or other publicity, without the prior written consent of
Landlord.
 
24.28     Building Directory.  Landlord shall include Tenant's name and location
and the name and location of any Affiliate Assignee, any Business Affiliate, any
Non-Affiliate Assignee and/or any applicable Major Subtenants in each Building
on one (1) line on the lobby directory for each such Building.  The initial cost
of such directory signage for Tenant shall be paid for by Landlord, but any
subsequent charges thereto, and the cost of any directory signage for any
Affiliate Assignee, any Business Affiliate, any Non-Affiliate Assignee or any
applicable Major Subtenants, shall be at Tenant's cost.
 
24.29     Intentionally Deleted.
 
24.30     Landlord's Construction.  Except as specifically set forth in this
Lease or in the Tenant Work Letter:  (i) Landlord has no obligation to alter,
remodel, improve, renovate, repair or decorate the Premises, the Buildings, the
Other Existing Buildings, the Project, or any part thereof; and (ii) no
representations or warranties respecting the condition of the Premises, the
Buildings, the Other Existing Buildings or the Project have been made by
Landlord to Tenant.  Tenant acknowledges that prior to and during the Lease
Term, Landlord (and/or any common area association) will be completing
construction and/or demolition work pertaining to various portions of the
Buildings, the Other Existing Buildings, the Premises, and/or the Project,
including without limitation, landscaping and tenant improvements for premises
for other tenants and, at Landlord's sole election, such other buildings,
improvements, landscaping and other facilities within or as part of the Project
as Landlord (and/or such common area association) shall from time to time desire
(collectively, the "Construction").  In connection with such Construction,
Landlord may, among other things, erect scaffolding or other necessary
structures in the Buildings and/or the Other Existing Buildings, limit or
eliminate access to portions of the Project, including portions of the common
areas, or perform work in the Buildings, the Other Existing Buildings and/or the
Project, which work may create noise, dust or leave debris in the Buildings, the
Other Existing Buildings and/or the Project.  Tenant hereby agrees that such
Construction and Landlord's actions in connection with such Construction shall
in no way constitute a constructive eviction of Tenant nor entitle Tenant to any
abatement of Rent (except as otherwise provided in Section 6.6 above).  Landlord
shall have no responsibility or for any reason be liable to Tenant for any
injury to or interference with Tenant's business arising from such Construction,
nor shall Tenant be entitled to any compensation or damages (subject to the
abatement provisions in Section 6.6 above) from Landlord for loss of the use of
the whole or any part of the Premises or of Tenant's personal property or
improvements resulting from such Construction or Landlord's actions in
connection with such Construction, or for any inconvenience or annoyance
occasioned by such Construction; provided, however, that Landlord shall remain
liable for personal injury and property damage resulting from any Construction
to the extent caused by Landlord’s or the Landlord Parties' gross negligence or
willful misconduct and not insured or required to be insured by Tenant under
this Lease.  Notwithstanding anything in this Section 24.30 to the contrary,
Landlord shall use commercially reasonable efforts to perform all Construction
in a manner, whenever reasonably practicable, to minimize any material, adverse
interference with Tenant’s normal business operations in the Premises.
 

 -26-
MARINA VILLAGE
[Biotime]

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

24.31     Emergency Generator.  Subject to (i) the approval of all applicable
governmental agencies, (ii) Tenant's compliance with all Applicable Laws and the
provisions of this Section 24.31 and the other provisions of this Lease, and
(iii) the provisions of, and Tenant's compliance with and obtaining all
approvals required under, all covenants, conditions and restrictions recorded
against the Project, Tenant shall have the exclusive right, at Tenant's sole
cost and expense and subject to the provisions of this Section 24.31, to utilize
the existing back-up emergency generator (the "Generator") in the location
depicted on Exhibit E attached hereto (the "Generator Site").  The Generator,
together with all platforms, fencing, enclosures, sheds and other related
materials and equipment shall be referred to herein as the "Generator
Equipment".  Tenant shall have the right, subject to available capacity of the
Building, to install such connection equipment, such as conduits, cables,
risers, feeders and materials (collectively, the "Generator Connecting
Equipment") in the shafts, ducts, conduits, chases, utility closets and other
facilities of the Building as is reasonably necessary to connect the Generator
Equipment to the Premises, and Tenant's other machinery and equipment therein,
subject, however, to the provisions of Section 24.31.2 below.  Tenant shall also
have the right of access, consistent with Section 24.31.3 below, to the areas
where the Generator Equipment and any such Generator Connecting Equipment are
located for the purposes of maintaining, repairing, testing and replacing the
same.  The Generator Equipment and related Generator Connecting Equipment are
hereby referred to together and/or separately as the "Emergency Power Supply
Equipment".
 
24.31.1      Emergency Power Supply Equipment.  The installation of the
Generator Connecting Equipment shall be performed in accordance with and subject
to the provisions of Article 8 above, and the Emergency Power Supply Equipment
shall be treated for all purposes of this Lease as if the same were Tenant's
personal property.  For purposes of determining Tenant's obligations with
respect to its use of the Generator Site and Emergency Power Supply Equipment
herein provided, the Generator Site shall be deemed to be a portion of the
Premises; consequently, all of the provisions of this Lease with respect to
Tenant's obligations hereunder shall apply to the installation, use and
maintenance of the Emergency Power Supply Equipment, including without
limitation, provisions relating to compliance with requirements as to insurance,
indemnity, repairs and maintenance, and compliance with Applicable Laws.
 
24.31.2      Non-Exclusive Right.  It is expressly understood that Landlord
retains the right to grant third parties the right to utilize any portion of the
Project located outside the Premises not utilized by Tenant as the Generator
Site, provided in each event that Tenant shall have reasonable access to, and
Landlord shall not unduly interfere with the use of, the Emergency Power Supply
Equipment.
 
24.31.3      Tenant's Covenants.  Tenant shall install, use, maintain and repair
the Emergency Power Supply Equipment so as not to damage or interfere with the
operation of the Building or Project or any portion thereof, including, without
limitation, the Generator Site, the systems and equipment, and any other
generators or power sources or similar equipment located in or on the Building
or Project; and Tenant hereby agrees to indemnify, defend and hold harmless from
and against any and all Claims arising out of Tenant's failure to comply with
the provisions of this Section 24.31.
 
24.31.4      Landlord's Obligations.  Landlord shall not have any obligations
with respect to the Generator Site, the Emergency Power Supply Equipment or
compliance with any requirements relating thereto, nor shall Landlord be
responsible for any damage that may be caused to the Emergency Power Supply
Equipment, except to the extent caused by the gross negligence or willful
misconduct of Landlord and not insured or required to be insured by Tenant under
this Lease.  Landlord makes no representation that the Emergency Power Supply
Equipment will be able to supply sufficient power to the Premises, and Tenant
agrees that Landlord shall not be liable to Tenant therefor.
 
24.31.5      Condition of Generator Site.  Tenant shall accept the Generator and
Generator Site in its "AS-IS" condition, without any representations or
warranties made by Landlord concerning same (including, but not limited to, the
purposes for which such areas are to be used by Tenant), and Landlord shall have
no obligation to contract or pay for any improvements or other work in or for
the Generator and/or Generator Site, and Tenant shall be solely responsible, at
its sole cost and expense, for constructing any improvements or performing any
other work in pertaining to the Emergency Power Supply Equipment and/or
Generator Site pursuant to and in accordance with the provisions of this Section
24.31.  Tenant, at Tenant's sole cost and expense, shall maintain the Emergency
Power Supply Equipment and install such enclosures, fencing and other protective
equipment on or about the Emergency Power Supply Equipment as Landlord may
reasonably determine.
 
24.31.6      Repairs.  Tenant shall (i) be solely responsible for any damage
caused as a result of the Emergency Power Supply Equipment, (ii) promptly pay
any tax, license or permit fees charged pursuant to any requirements in
connection with the installation, maintenance or use of the Emergency Power
Supply Equipment and comply with all precautions and safeguards recommended by
all governmental authorities, and (iii) make necessary repairs, replacements to
or maintenance of the Emergency Power Supply Equipment and Generator Site. 
Tenant shall have the work which is Tenant's obligation to perform under this
Section 24.31 (including, without limitation, all installation, modification and
maintenance of the Emergency Power Supply Equipment) performed promptly and
diligently in a first-class, workmanlike manner, by contractors and
subcontractors approved by Landlord.
 
24.31.7      Installation.  Tenant shall install and operate the Emergency Power
Supply Equipment in compliance with all Applicable Laws.  Prior to the
installation of the Emergency Power Supply Equipment, or the performance of any
modifications or changes thereto, Tenant shall comply with the following:
 
24.31.7.1                  Tenant shall submit to Landlord in writing all plans
for such installations, modifications or changes for Landlord's approval, which
approval shall be granted or denied in Landlord's sole and absolute discretion;
 
24.31.7.2                  prior to commencement of any work, Tenant shall
obtain the required approvals of all federal, state and local governmental
authorities; Tenant shall promptly deliver to Landlord written proof of
compliance with all Applicable Laws in connection with any work related to the
Emergency Power Supply Equipment, including, but not limited to, a signed-off
permit from the City of Alameda;
 

 -27-
MARINA VILLAGE
[Biotime]

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

24.31.7.3                 all of such work shall conform to Landlord's design
specifications for the Building, Project and the Generator Site and Landlord's
requirements, including, but not limited to, weight and loading requirements,
and shall not adversely affect the structural components of the Building or
interfere with any systems and equipment located in, upon or serving the
Project, Building or the Generator Site; and
 
24.31.7.4                  the Emergency Power Supply Equipment shall be clearly
marked to show Tenant's name, address, telephone number and the name of the
person to contact in case of emergency.
 
24.31.8      Hazardous Materials.  Tenant shall not use any Hazardous Materials
in connection with the Emergency Power Supply Equipment, except that Tenant may
use diesel fuel stored in a double walled steel tank (the "Fuel Tank") contained
within the Generator, as long as such fuel and such Fuel Tank are kept,
maintained and used in accordance with all Applicable Laws and the highest
safety standards for such use, and so long as such fuel is always stored within
the Fuel Tank and is not used or stored in any area outside of the Generator. 
Tenant shall promptly, at Tenant's expense, take all investigatory and all
remedial action required by Applicable Laws and reasonably recommended by
Landlord, whether or not formally ordered or required by Applicable Laws, for
the cleanup of any spill, release or other contamination of the Generator Site
and/or the Project to the extent caused or contributed to by Tenant's use of the
Emergency Power Supply Equipment (including, without limitation, the fuel for
the Generator), or pertaining to or involving any such fuel or other Hazardous
Materials brought onto the Generator Site during the Lease Term by Tenant or any
of Tenant's agents, employees, contractors, licensees or invitees.  Tenant shall
indemnify, defend and hold Landlord harmless from and against any and all Claims
to the extent arising out of or involving any Hazardous Materials brought onto
the Generator Site by or for Tenant in connection with Tenant's activities under
this Section 24.31.  Tenant's obligations shall include, but not be limited to,
the effects of any contamination or injury to person, property or the
environment created or suffered by Tenant or any of Tenant's agents, employees,
licensees or invitees, and the cost of investigation, removal, remediation,
restoration and/or abatement, and shall survive the expiration or termination of
this Lease.
 
24.31.9    Security.  Physical security of the Generator Site and the Emergency
Power Supply Equipment is the sole responsibility of Tenant, who shall bear the
sole cost, expense and liability of any security services, emergency alarm
monitoring and other similar services in connection therewith.  Landlord shall
not be liable to Tenant for any damages (including Consequential Damages)
arising out of or in connection with the physical security, or lack thereof, of
the Generator Site and/or Emergency Power Supply Equipment.
 
24.31.10   Testing.  The Emergency Power Supply Equipment shall be routinely
tested and inspected by a qualified contractor selected by Tenant and reasonably
approved by Landlord, at Tenant's expense, in accordance with testing and
inspection service contracts reasonably approved by Landlord.  Tenant will
provide Landlord with copies of certificates and other documentation related to
the testing of the Emergency Power Supply Equipment.  Testing hours are
restricted, however, to those specific hours reasonably set and determined by
Landlord from time to time.
 
24.31.11   Default.  If Tenant fails to perform any of its obligations under
this Section 24.31, and does not correct such noncompliance within five (5)
business days after receipt of notice thereof from Landlord or such longer
period as may be reasonably necessary to correct such noncompliance, so long as
Tenant commences to correct such noncompliance within such five (5) business day
period and thereafter proceeds with due diligence to correct such noncompliance,
then Tenant shall be deemed in default under this Lease, notwithstanding any
other notice or cure provided in Article 19 above or otherwise in this Lease,
and in addition to all other remedies Landlord may have under this Lease, Tenant
shall, upon notice from Landlord, immediately discontinue its use of that
portion of the Emergency Power Supply Equipment to which such noncompliance
relates, and make such repairs and restoration as required under Section
24.33.12 below with respect thereto.
 
24.31.12   Removal at End of Lease Term.  Upon the expiration or earlier
termination of this Lease, Tenant shall not remove the Emergency Power Supply
Equipment.
 
24.31.13   Rights Personal.  Notwithstanding the foregoing provisions of this
Section 24.31 to the contrary, Tenant's rights under this Section 24.31:  (i)
shall only be available to and exercisable by the Original Tenant, or any
Affiliate Assignee, Business Affiliate, Non-Affiliate Assignee, any applicable
Major Subtenants, or any other Transferee of a Transfer approved by Landlord if
Landlord approves in writing of such Transferee's use thereof (as the case may
be); and (ii) may not be transferred to or used by any person or entity other
than the Original Tenant or such Affiliate Assignee, Business Affiliate,
Non-Affiliate Assignee, any applicable Major Subtenants, or any other Transferee
of a Transfer approved by Landlord if Landlord approves in writing of such
Transferee's use thereof (as the case may be).
 
24.32     Liquid Nitrogen Tank.  Subject to (i) the approval of all applicable
governmental agencies, (ii) Tenant's compliance with all Applicable Laws and the
provisions of this Section 24.32 and the other provisions of this Lease, and
(iii) the provisions of, and Tenant's compliance with and obtaining all
approvals required under, all covenants, conditions and restrictions recorded
against the Project, Tenant shall have the exclusive right, at Tenant's sole
cost and expense and subject to the provisions of this Section 24.32, to install
one liquid nitrogen tank (the "Liquid Nitrogen Tank") in a location located
outside the Premises as shall be designated by Landlord in Landlord's sole
discretion (the area upon which the Liquid Nitrogen Tank shall be located shall
be referred to herein as the "Liquid Nitrogen Tank Site").  The Liquid Nitrogen
Tank shall be of such size and specifications, and include such platforms,
fencing, enclosures, sheds and other related materials and equipment, as shall
be approved by Landlord prior to installation (collectively, the "Liquid
Nitrogen Tank Equipment"), which approval may be granted or denied in Landlord's
sole and absolute discretion.  In addition, Tenant shall have the right, subject
to available capacity of the Building, to install such connection equipment,
such as conduits, cables, risers, feeders and materials (collectively, the
"Liquid Nitrogen Tank Connecting Equipment") in the shafts, ducts, conduits,
chases, utility closets and other facilities of the Building as is reasonably
necessary to connect the Liquid Nitrogen Tank Equipment to the Premises, and
Tenant's other machinery and equipment therein, subject, however, to the
provisions of Section 24.32.2 below.  Tenant shall also have the right of
access, consistent with Section 24.32.3 below, to the areas where the Liquid
Nitrogen Tank Equipment and any such Liquid Nitrogen Tank Connecting Equipment
are located for the purposes of maintaining, repairing, testing and replacing
the same.
 

 -28-
MARINA VILLAGE
[Biotime]

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

24.32.1      Liquid Nitrogen Supply Equipment.  The installation of the Liquid
Nitrogen Tank Equipment and related Liquid Nitrogen Tank Connecting Equipment
(hereby referred to together and/or separately as the "Liquid Nitrogen Supply
Equipment") shall be performed in accordance with and subject to the provisions
of Article 8 above, and the Liquid Nitrogen Supply Equipment shall be treated
for all purposes of this Lease as if the same were Tenant's personal property. 
For purposes of determining Tenant's obligations with respect to its use of the
Liquid Nitrogen Tank Site and Liquid Nitrogen Supply Equipment herein provided,
the Liquid Nitrogen Tank Site shall be deemed to be a portion of the Premises;
consequently, all of the provisions of this Lease with respect to Tenant's
obligations hereunder shall apply to the installation, use and maintenance of
the Liquid Nitrogen Supply Equipment, including without limitation, provisions
relating to compliance with requirements as to insurance, indemnity, repairs and
maintenance, and compliance with Applicable Laws.
 
24.32.2      Non-Exclusive Right.  It is expressly understood that Landlord
retains the right to grant third parties the right to utilize any portion of the
Project located outside the Premises not utilized by Tenant as the Liquid
Nitrogen Tank Site, provided in each event that Tenant shall have reasonable
access to, and Landlord shall not unduly interfere with the use of, the Liquid
Nitrogen Supply Equipment.
 
24.32.3      Tenant's Covenants.  Tenant shall install, use, maintain and repair
the Liquid Nitrogen Supply Equipment so as not to damage or interfere with the
operation of the Building or Project or any portion thereof, including, without
limitation, the Liquid Nitrogen Tank Site, the systems and equipment, and any
other power sources or similar equipment located in or on the Building or
Project; and Tenant hereby agrees to indemnify, defend and hold harmless from
and against any and all Claims arising out of Tenant's failure to comply with
the provisions of this Section 24.32.
 
24.32.4      Landlord's Obligations.  Landlord shall not have any obligations
with respect to the Liquid Nitrogen Tank Site, the Liquid Nitrogen Supply
Equipment or compliance with any requirements relating thereto, nor shall
Landlord be responsible for any damage that may be caused to the Liquid Nitrogen
Supply Equipment, except to the extent caused by the gross negligence or willful
misconduct of Landlord and not insured or required to be insured by Tenant under
this Lease.
 
24.32.5      Condition of Liquid Nitrogen Tank Site.  Tenant shall accept the
Liquid Nitrogen Tank Site in its "AS-IS" condition, without any representations
or warranties made by Landlord concerning same (including, but not limited to,
the purposes for which such areas are to be used by Tenant), and Landlord shall
have no obligation to contract or pay for any improvements or other work in or
for the Liquid Nitrogen Tank Site, and Tenant shall be solely responsible, at
its sole cost and expense, for preparing the Liquid Nitrogen Tank Site for the
installation of the Liquid Nitrogen Supply Equipment and for constructing any
improvements or performing any other work in such areas pursuant to and in
accordance with the provisions of this Section 24.32.  Tenant, at Tenant's sole
cost and expense, shall maintain the Liquid Nitrogen Supply Equipment and
install such enclosures, fencing and other protective equipment on or about the
Liquid Nitrogen Supply Equipment as Landlord may reasonably determine.
 
24.32.6      Repairs.  Tenant shall (i) be solely responsible for any damage
caused as a result of the Liquid Nitrogen Supply Equipment, (ii) promptly pay
any tax, license or permit fees charged pursuant to any requirements in
connection with the installation, maintenance or use of the Liquid Nitrogen
Supply Equipment and comply with all precautions and safeguards recommended by
all governmental authorities, and (iii) make necessary repairs, replacements to
or maintenance of the Liquid Nitrogen Supply Equipment and Liquid Nitrogen Tank
Site.  Tenant shall have the work which is Tenant's obligation to perform under
this Section 24.32 (including, without limitation, all installation,
modification and maintenance of the Liquid Nitrogen Supply Equipment) performed
promptly and diligently in a first-class, workmanlike manner, by contractors and
subcontractors approved by Landlord.
 
24.32.7      Installation.  Tenant shall install and operate the Liquid Nitrogen
Supply Equipment in compliance with all Applicable Laws.  Prior to the
installation of the Liquid Nitrogen Supply Equipment, or the performance of any
modifications or changes thereto, Tenant shall comply with the following:
 
24.32.7.1                  Tenant shall submit to Landlord in writing all plans
for such installations, modifications or changes for Landlord's approval, which
approval shall be granted or denied in Landlord's sole and absolute discretion;
 
24.32.7.2                  prior to commencement of any work, Tenant shall
obtain the required approvals of all federal, state and local governmental
authorities; Tenant shall promptly deliver to Landlord written proof of
compliance with all Applicable Laws in connection with any work related to the
Liquid Nitrogen Supply Equipment, including, but not limited to, a signed-off
permit from the City of Alameda;
 
24.32.7.3                  all of such work shall conform to Landlord's design
specifications for the Building, Project and the Liquid Nitrogen Tank Site and
Landlord's requirements, including, but not limited to, weight and loading
requirements, and shall not adversely affect the structural components of the
Building or interfere with any systems and equipment located in, upon or serving
the Project, Building or the Liquid Nitrogen Tank Site; and
 

 -29-
MARINA VILLAGE
[Biotime]

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

24.32.7.4                  the Liquid Nitrogen Supply Equipment shall be clearly
marked to show Tenant's name, address, telephone number and the name of the
person to contact in case of emergency.
 
24.32.8      Hazardous Materials.  Tenant shall not use any Hazardous Materials
in connection with the Liquid Nitrogen Supply Equipment, other than liquid
nitrogen contained within the Liquid Nitrogen Tank if the Liquid Nitrogen Tank
is installed by Tenant pursuant to the foregoing provisions of this Section
24.32, as long as such liquid nitrogen is kept, maintained and used in
accordance with all Applicable Laws and the highest safety standards for such
use, and so long as such liquid nitrogen is not used or stored in any area
outside of the Liquid Nitrogen Tank.  Tenant shall promptly, at Tenant's
expense, take all investigatory and all remedial action required by Applicable
Laws and reasonably recommended by Landlord, whether or not formally ordered or
required by Applicable Laws, for the cleanup of any spill, release or other
contamination of the Liquid Nitrogen Tank Site and/or the Project to the extent
caused or contributed to by Tenant's use of the Liquid Nitrogen Supply Equipment
(including, without limitation, the liquid nitrogen for the Liquid Nitrogen
Tank), or pertaining to or involving any such liquid nitrogen or other Hazardous
Materials brought onto the Liquid Nitrogen Tank Site during the Lease Term by
Tenant or any of Tenant's agents, employees, contractors, licensees or
invitees.  Tenant shall indemnify, defend and hold Landlord harmless from and
against any and all Claims to the extent arising out of or involving any
Hazardous Materials brought onto the Liquid Nitrogen Tank Site by or for Tenant
in connection with Tenant's activities under this Section 24.32.  Tenant's
obligations shall include, but not be limited to, the effects of any
contamination or injury to person, property or the environment created or
suffered by Tenant or any of Tenant's agents, employees, licensees or invitees,
and the cost of investigation, removal, remediation, restoration and/or
abatement, and shall survive the expiration or termination of this Lease.
 
24.32.9      Security.  Physical security of the Liquid Nitrogen Tank Site and
the Liquid Nitrogen Supply Equipment is the sole responsibility of Tenant, who
shall bear the sole cost, expense and liability of any security services,
emergency alarm monitoring and other similar services in connection therewith. 
Landlord shall not be liable to Tenant for any damages (including Consequential
Damages) arising out of or in connection with the physical security, or lack
thereof, of the Liquid Nitrogen Tank Site and/or Liquid Nitrogen Supply
Equipment.
 
24.32.10   Testing.  The Liquid Nitrogen Supply Equipment shall be routinely
tested and inspected by a qualified contractor selected by Tenant and reasonably
approved by Landlord, at Tenant's expense, in accordance with testing and
inspection service contracts reasonably approved by Landlord.  Tenant will
provide Landlord with copies of certificates and other documentation related to
the testing of the Liquid Nitrogen Supply Equipment.  Testing hours are
restricted, however, to those specific hours reasonably set and determined by
Landlord from time to time.
 
24.32.11   Default.  If Tenant fails to perform any of its obligations under
this Section 24.32, and does not correct such noncompliance within five (5)
business days after receipt of notice thereof from Landlord or such longer
period as may be reasonably necessary to correct such noncompliance, so long as
Tenant commences to correct such noncompliance within such five (5) business day
period and thereafter proceeds with due diligence to correct such noncompliance,
then Tenant shall be deemed in default under this Lease, notwithstanding any
other notice or cure provided in Article 19 above or otherwise in this Lease,
and in addition to all other remedies Landlord may have under this Lease, Tenant
shall, upon notice from Landlord, immediately discontinue its use of that
portion of the Liquid Nitrogen Supply Equipment to which such noncompliance
relates, and make such repairs and restoration as required under Section
24.32.12 below with respect thereto.
 
24.32.12  Removal at End of Lease Term.  Upon the expiration or earlier
termination of this Lease, Tenant shall, subject to the control of and direction
from Landlord, remove the Liquid Nitrogen Supply Equipment, including, without
limitation all electrical switch gear, underground conduit and feeders,
architectural enclosure and/or modifications to the Liquid Nitrogen Tank Site,
repair any damage caused thereby, and restore the Liquid Nitrogen Tank Site and
other facilities of the Building and Project to their condition existing prior
to the installation of the Liquid Nitrogen Supply Equipment.  Any and all
removal of the Liquid Nitrogen Supply Equipment shall be performed by certified
and licensed contractors previously approved in writing by Landlord (which
approval shall not be unreasonably withheld, conditioned or delayed) and in
accordance with a previously approved removal plan, in a workmanlike manner,
without any interference, damage or destruction to any other equipment,
structures or operations at the Liquid Nitrogen Tank Site, the Building or the
Project and/or any equipment of other licensees or tenants.  If Tenant fails to
timely make such removal and/or restoration, then Landlord may perform such work
at Tenant's cost, which cost shall be immediately due and payable to Landlord
upon Tenant's receipt of invoice therefor from Landlord.
 
24.32.13  Rights Personal.  Notwithstanding the foregoing provisions of this
Section 24.32 to the contrary, Tenant's rights under this Section 24.32:  (i)
shall only be available to and exercisable by the Original Tenant, or any
Affiliate Assignee, Business Affiliate, Non-Affiliate Assignee, any applicable
Major Subtenants, or any other Transferee of a Transfer approved by Landlord if
Landlord approves in writing of such Transferee's use thereof (as the case may
be); and (ii) may not be transferred to or used by any person or entity other
than the Original Tenant or such Affiliate Assignee, Business Affiliate,
Non-Affiliate Assignee, any applicable Major Subtenants, or any other Transferee
of a Transfer approved by Landlord if Landlord approves in writing of such
Transferee's use thereof (as the case may be).
 
[SIGNATURES ON FOLLOWING PAGE]
 

 -30-
MARINA VILLAGE
[Biotime]

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

IN WITNESS WHEREOF, Landlord and Tenant have caused this Lease to be executed
the day and date first above written.
 

 
"Landlord":
             
BSREP MARINA VILLAGE OWNER LLC,
   
a Delaware limited liability company
         
By:
 
/s/Thomas Diamond
   
Name:   Thomas Diamond
   
Its:   Vice President
 

 

 
"Tenant":
             
BIOTIME, INC.,
   
a California corporation
         
By:
/s/ Aditya Mohanty
           
Name: Adi Monaty
   
Its: Co-CEO
         
By:
/s/ Judith Segall
     
Name: Judith Segall
     
Its:  VP & Corporate Secretary
 

 
*** If Tenant is a CORPORATION, the authorized officers must sign on behalf of
the corporation and indicate the capacity in which they are signing.  The Lease
must be executed by the president or vice president and the secretary or
assistant secretary, unless the bylaws or a resolution of the board of directors
shall otherwise provide, in which event, the bylaws or a certified copy of the
resolution, as the case may be, must be attached to this Lease.
 

 -31-
MARINA VILLAGE
[Biotime]

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

EXHIBIT A-1
 
OUTLINE OF FLOOR PLAN OF 1010 PREMISES
 
[image0.jpg]
 
 EXHIBIT A-1
-1-
MARINA VILLAGE
[Biotime]

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

EXHIBIT A-2

OUTLINE OF FLOOR PLAN OF 1020 PREMISES
 
[image1.jpg]
 
 EXHIBIT A-2
-1-
MARINA VILLAGE
[Biotime]

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

EXHIBIT A-3
 
SITE PLAN OF PROJECT
 
[image2.jpg]
 
 EXHIBIT A-3
-1-
MARINA VILLAGE
[Biotime]

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

EXHIBIT A-4

DEPICTION OF 1010 OFFICE SPACE AND 1010 LAB SPACE
 
[image3.jpg]
 
 EXHIBIT A-4
-1-
MARINA VILLAGE
[Biotime]

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

EXHIBIT B
 
TENANT WORK LETTER
 
This Tenant Work Letter ("Tenant Work Letter") shall set forth the terms and
conditions relating to the construction of the Premises.  All references in this
Tenant Work Letter to the "Lease" shall mean the relevant portions of the Lease
to which this Tenant Work Letter is attached as Exhibit B.

SECTION 1

BASE, SHELL AND CORE
 
Landlord has previously constructed the base, shell and core (i) of the Premises
and (ii) of the floor(s) of the Buildings on which the Premises are located
(collectively, the "Base, Shell and Core"), and Tenant shall accept the Base,
Shell and Core in its current "As-Is" condition existing as of the date of the
Lease and the Lease Commencement Date.  Except for the Tenant Improvement
Allowance set forth below and except as expressly provided in Section 7.2 of the
Lease, Landlord shall not be obligated to make or pay for any alterations or
improvements to the Premises, the Buildings or the Project.
 
SECTION 2

TENANT IMPROVEMENTS
 
2.1           Tenant Improvement Allowance.  Tenant shall be entitled to a
one-time tenant improvement allowance (the "Initial Allowance") in the amount of
up to, but not exceeding Forty-Five Dollars ($45.00) per rentable square foot of
the Premises (i.e., up to One Million, Three Hundred Eighty-Five Thousand, Seven
Hundred Seventy-Five and 00/100 Dollars ($1,385,775.00) based on 30,795 rentable
square feet of the Premises), to help Tenant pay for the costs of the design,
permitting and construction of Tenant's initial improvements which are
permanently affixed to the Premises (collectively, the "Tenant Improvements"). 
Notwithstanding the foregoing, if there is an Over-Allowance Amount (as defined
below), then Tenant shall have the option, exercisable upon written notice to
Landlord prior to the date Tenant is obligated to pay such Over-Allowance Amount
to Landlord pursuant to Section 4.2.1 below, to receive an additional one-time
tenant improvement allowance to help pay for such Over-Allowance Amount (the
"Additional Allowance") in the amount of up to, but not exceeding $307,950.00
(i.e., $10.00 per rentable square foot of the Premises).  As consideration for
Landlord providing the Additional Allowance to Tenant, the amount of the
Additional Allowance provided by Landlord shall be amortized on a monthly basis
over the scheduled seven (7) year initial Lease Term at an interest rate of ten
percent (10%) per annum, and each such monthly payment of amortization and
interest (collectively, the "Amortization Rent") shall be paid by Tenant to
Landlord as an increase in the Base Rent, or at Landlord's option as Additional
Rent, on or prior to the first (1st) day of each month throughout such seven (7)
year initial Lease Term.  If the Lease shall terminate for any reason, including
without limitation as a result of a default by Tenant under the terms of the
Lease or this Tenant Work Letter, Tenant acknowledges and agrees that the
unamortized balance of the Additional Allowance which has not been paid by
Tenant to Landlord as of the termination date pursuant to the foregoing
provisions of this Section 2.1 shall become immediately due and payable as
unpaid rent which has been earned as of such termination date, specifically
including a termination pursuant to Article 19 of the Lease.  In addition, in no
event shall the Amortization Rent be abated for any reason whatsoever, including
without limitation, pursuant to Articles 11 and 12 of the Lease.  The Initial
Allowance and the portion of the Additional Allowance so elected to be received
by Tenant are sometimes collectively referred to herein as the "Tenant
Improvement Allowance."  Notwithstanding anything to the contrary contained in
this Tenant Work Letter, Landlord shall have no obligation to disburse all or
any portion of the Tenant Improvement Allowance to Tenant unless Tenant makes a
request for disbursement pursuant to the terms and conditions of Section 2.2
below prior to that date which is twelve (12) months after the Lease
Commencement Date.  In no event shall Landlord be obligated to make
disbursements pursuant to this Tenant Work Letter in a total amount which
exceeds the Tenant Improvement Allowance.  In addition, Tenant shall not be
entitled to receive any cash payment or credit against Rent or otherwise for any
unused portion of the Tenant Improvement Allowance which is not used to pay for
the Tenant Improvement Allowance Items (as defined below).
 
2.2           Disbursement of the Tenant Improvement Allowance.
 
2.2.1            Tenant Improvement Allowance Items.  Except as otherwise set
forth in this Tenant Work Letter, the Tenant Improvement Allowance shall be
disbursed by Landlord only for the following items and costs (collectively, the
"Tenant Improvement Allowance Items"):
 
2.2.1.1                     Payment of (i) the fees of the Architect and the
Engineers (as such terms are defined below), and (ii) the fees incurred by, and
the cost of documents and materials supplied by, Landlord and Landlord's
consultants in connection with the preparation and review of the Construction
Drawings (as defined below);
 
2.2.1.2                     The payment of plan check, permit and license fees
relating to construction of the Tenant Improvements;
 
2.2.1.3                     The cost of construction of the Tenant Improvements,
including, without limitation, contractors' fees and general conditions, testing
and inspection costs, costs of utilities, trash removal, parking and hoists, and
the costs of after-hours freight elevator usage and the cost of all materials,
supplies, equipment and fixtures comprising a part of or related to the
construction of the Tenant Improvements.
 
 EXHIBIT B
-1-
MARINA VILLAGE
[Biotime]

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

2.2.1.4                     The cost of any changes in the Base, Shell and Core
work when such changes are required by the Construction Drawings (including if
such changes are due to the fact that such work is prepared on an unoccupied
basis), such cost to include all direct architectural and/or engineering fees
and expenses incurred in connection therewith;
 
2.2.1.5                     The cost of any changes to the Construction Drawings
or Tenant Improvements required by Applicable Laws;
 
2.2.1.6                     Sales and use taxes and Title 24 fees;
 
2.2.1.7                     the costs and expenses associated with complying
with all national, state and local codes, including California Energy Code,
Title 24, including, without limitation, all costs associated with any lighting
or HVAC retrofits required thereby;
 
2.2.1.8                     the Coordination Fee (as defined below); and
 
2.2.1.9                     All other costs to be expended by Landlord in
connection with the design, permitting and construction of the Tenant
Improvements.
 
2.2.2            Disbursement of Tenant Improvement Allowance.  Subject to
Section 2.1 above, during the construction of the Tenant Improvements, Landlord
shall make monthly disbursements of the Tenant Improvement Allowance for Tenant
Improvement Allowance Items for the benefit of Tenant and shall authorize the
release of monies for the benefit of Tenant as follows:
 
2.2.2.1                     Monthly Disbursements.  From time to time during the
construction of the Tenant Improvements (but no more frequently than monthly),
Tenant shall deliver to Landlord:  (i) a request for payment of the Contractor
(as defined below), approved by Tenant, in a form to be provided by Landlord,
showing the schedule, by trade, of percentage of completion of the Tenant
Improvements in the Premises, detailing the portion of the work completed and
the portion not completed, and demonstrating that the relationship between the
cost of the work completed and the cost of the work to be completed complies
with the terms of the Construction Budget (as defined below); (ii) invoices from
all of Tenant's Agents (as defined below), for labor rendered and materials
delivered to the Premises; (iii) executed mechanic's lien releases from all of
Tenant's Agents which shall comply with the appropriate provisions, as
reasonably determined by Landlord, of California Civil Code Sections 8132
through 8138; and (iv) each of the general disbursement items referenced in
Section 2.2.2.2 below, and all other information reasonably requested by
Landlord.  Tenant's request for payment shall be deemed Tenant's acceptance and
approval of the work furnished and/or the materials supplied as set forth in
Tenant's payment request.  Following Landlord's receipt of a completed
disbursement request submission, Landlord shall deliver a check to Tenant made
jointly payable to the Contractor and Tenant in payment of the lesser of (A) the
amounts so requested by Tenant, as set forth in this Section 2.2.2.1, above,
less a ten percent (10%) retention (the aggregate amount of such retentions to
be known as the "Final Retention") and (B) the balance of any remaining
available portion of the Tenant Improvement Allowance (not including the Final
Retention), provided that Landlord does not dispute any request for payment
based on non-compliance of any work with the Approved Working Drawings (as
defined below), or due to any substandard work, or for any other reason.
 
2.2.2.2                      Final Retention.  Subject to the provisions of this
Tenant Work Letter, a check for the Final Retention payable jointly to Tenant
and the Contractor shall be delivered by Landlord to Tenant following the
completion of construction of the Premises, provided that (i) Landlord has
determined that no substandard work exists which adversely affects the
mechanical, electrical, plumbing, HVAC, life-safety or other systems of the
Buildings, the curtain wall of the Buildings, the structure or exterior
appearance of the Buildings, or any other tenant's use of such other tenant's
leased premises in the Buildings; and (ii) Tenant has delivered to Landlord: 
(A) properly executed and final unconditional mechanics lien releases in
compliance with applicable California law; (B) a certificate of occupancy or
permit cards signed off by the City of Alameda (the "City") with respect to the
Leased Premises; (C) as-built plans and City-permitted plans for the Tenant
Improvements; (D) operation manuals and warranties for equipment included within
the Tenant Improvements, if applicable; (E) copy of the contract with the
Contractor; (F) copy of the Contractor's certificate of insurance, including
Additional Insured endorsement naming Landlord as additional insureds; and (G)
the Contractor's schedule of values, showing total contract value.
 
2.2.2.3                      Other Terms.  Landlord shall only be obligated to
make disbursements from the Tenant Improvement Allowance to the extent costs are
incurred by Tenant for Tenant Improvement Allowance Items.
 
SECTION 3

CONSTRUCTION DRAWINGS
 
3.1         Selection of Architect/Construction Drawings.  Tenant shall retain
the architect/space planner (the "Architect") approved by Landlord, which
approval shall not be unreasonably withheld, to prepare the Construction
Drawings.  Tenant shall retain the engineering consultants designated by
Landlord (the "Engineers") to prepare all plans and engineering working drawings
relating to the structural, mechanical, electrical, plumbing, HVAC, lifesafety,
and sprinkler work in the Premises.  The plans and drawings to be prepared by
Architect and the Engineers hereunder shall be known collectively as the
"Construction Drawings."  All Construction Drawings shall comply with the
drawing format and specifications reasonably determined by Landlord, and shall
be subject to Landlord's approval.  Tenant and Architect shall verify, in the
field, the dimensions and conditions as shown on the relevant portions of the
base building plans, and Tenant and Architect shall be solely responsible for
the same, and Landlord shall have no responsibility in connection therewith. 
Landlord's review of the Construction Drawings as set forth in this Section 3,
shall be for its sole purpose and shall not imply Landlord's review of the same,
or obligate Landlord to review the same, for quality, design, Code compliance or
other like matters.  Accordingly, notwithstanding that any Construction Drawings
are reviewed by Landlord or its space planner, architect, engineers and
consultants, and notwithstanding any advice or assistance which may be rendered
to Tenant by Landlord or Landlord's space planner, architect, engineers, and
consultants, Landlord shall have no liability whatsoever in connection therewith
and shall not be responsible for any omissions or errors contained in the
Construction Drawings.
 
 EXHIBIT B
-2-
MARINA VILLAGE
[Biotime]

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

3.2           Final Space Plan.  Tenant shall supply Landlord with four (4)
copies signed by Tenant of its final space plan for the Premises before any
architectural working drawings or engineering drawings have been commenced.  The
final space plan (the "Final Space Plan") shall include a layout and designation
of all offices, rooms and other partitioning, their intended use, and equipment
to be contained therein.  Landlord may request clarification or more specific
drawings for special use items not included in the Final Space Plan.  Landlord
shall advise Tenant within five (5) business days after Landlord's receipt of
the Final Space Plan for the Premises if the same is unsatisfactory or
incomplete in any respect.  If Tenant is so advised, Tenant shall promptly (i)
cause the Final Space Plan to be revised to correct any deficiencies or other
matters Landlord may reasonably require, and (ii) deliver such revised Final
Space Plan to Landlord.
 
3.3           Final Working Drawings.  After the Final Space Plan has been
approved by Landlord and Tenant, Tenant shall promptly cause the Architect and
the Engineers to complete the architectural and engineering drawings for the
Premises, and cause the Architect to compile a fully coordinated set of
architectural, structural, mechanical, electrical and plumbing working drawings
in a form which is complete to allow subcontractors to bid on the work and to
obtain all applicable permits for the Tenant Improvements and which shall
include a list of all specifications to be used in connection with the Tenant
Improvements, which shall in all events be consistent with the character of the
Buildings as first-class office and R&D buildings (collectively, the "Final
Working Drawings"), and shall submit the same to Landlord for Landlord's
approval.  Tenant shall supply Landlord with four (4) copies signed by Tenant of
such Final Working Drawings.  Landlord shall advise Tenant within five (5)
business days after Landlord's receipt of the Final Working Drawings for the
Premises if the same is unsatisfactory or incomplete in any respect.  If Tenant
is so advised, Tenant shall promptly (i) revise the Final Working Drawings in
accordance with such review and any disapproval of Landlord in connection
therewith, and (ii) deliver such revised Final Working Drawings to Landlord for
Landlord's approval, and the foregoing procedure shall be repeated until the
Final Working Drawings are approved by Landlord (which approved Final Working
Drawings shall be referred to herein as the "Approved Working Drawings").
 
3.4          Approved Working Drawings.  After Landlord approves of the Approved
Working Drawings, Tenant shall promptly submit the same to the appropriate
governmental authorities for all applicable building permits.  Tenant hereby
agrees that neither Landlord nor Landlord's consultants shall be responsible for
obtaining any building permit or certificate of occupancy for the Premises and
that obtaining the same shall be Tenant's responsibility; provided, however,
that Landlord shall cooperate with Tenant in executing permit applications and
performing other ministerial acts reasonably necessary to enable Tenant to
obtain any such permit or certificate of occupancy.  No changes, modifications
or alterations in the Approved Working Drawings may be made without the prior
written consent of Landlord, which consent shall not be unreasonably withheld;
provided that Landlord may withhold its consent, in its sole discretion, to any
change in the Approved Working Drawings, if such change would result in an
Over-Allowance Cap (as defined below).
 
SECTION 4

CONSTRUCTION OF THE TENANT IMPROVEMENTS
 
4.1           Tenant's Selection of Contractor and Tenant's Agents.
 
4.1.1            The Contractor.  Tenant shall select and retain a general
contractor to construct the Tenant Improvements through a competitive bidding
process which shall include general contractors approved by Landlord.  The
general contractor chosen by Tenant from the approved list of bidders shall be
the general contractor submitting the lowest cost bid, unless otherwise approved
by Landlord.  Following such competitive bidding process and Tenant's selection
of a general contractor in accordance with the terms hereof, Tenant shall
deliver to Landlord notice of its selection of the general contractor upon such
selection, which contractor shall thereafter be the "Contractor" hereunder.
 
4.1.2            Tenant's Agents.  All subcontractors, laborers, materialmen,
and suppliers used by Tenant (such subcontractors, laborers, materialmen, and
suppliers, and the Contractor to be known collectively as "Tenant's Agents")
must be approved in writing by Landlord, which approval shall not be
unreasonably withheld or delayed; provided that, in any event, Tenant must
contract with Landlord's base building subcontractors for any mechanical,
electrical, plumbing, life safety, structural, and HVAC work in the Premises. 
If requested by Landlord, Tenant's Agents shall all be union labor in compliance
with the master labor agreements existing between trade unions and the local
chapter of the Associated General Contractors of America.
 
 EXHIBIT B
-3-
MARINA VILLAGE
[Biotime]

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

4.2           Construction of Tenant Improvements by Tenant's Agents.
 
4.2.1           Construction Contract; Cost Budget. Prior to Tenant's execution
of the construction contract and general conditions with the Contractor (the
"Contract"), Tenant shall submit the Contract to Landlord for its approval,
which approval shall not be unreasonably withheld or delayed. Prior to the
commencement of the construction of the Tenant Improvements, and after Tenant
has accepted all bids for the Tenant Improvements, Tenant shall provide Landlord
with a written detailed cost breakdown (the "Final Costs Statement"), by trade,
of the final costs to be incurred, or which have been incurred, as set forth
more particularly in Section 2.2.1.1 through 2.2.1.8 above, in connection with
the design, permitting and construction of the Tenant Improvements to be
performed by or at the direction of Tenant or the Contractor (which costs form a
basis for the amount of the Contract, if any (the "Final Costs"). Prior to the
commencement of construction of the Tenant Improvements, unless and to the
extent that Tenant has timely elected to receive any Additional Allowance from
Landlord pursuant to Section 2.1 above, Tenant shall supply Landlord with cash
in an amount (the "Over-Allowance Amount") by which the Final Costs exceed the
Initial Allowance (less any portion thereof already disbursed by Landlord, or in
the process of being disbursed by Landlord, on or before the commencement of
construction of the Tenant Improvements). The Over-Allowance Amount (to the
extent not paid out of the Additional Allowance, if applicable) shall be
disbursed by Landlord prior to the disbursement of any of the then remaining
portion of the Initial Allowance, and such disbursement shall be pursuant to the
same procedure as the Tenant Improvement Allowance. If, after the Final Costs
have been delivered by Landlord to Tenant, the costs relating to the design,
permitting and construction of the Tenant Improvements shall change, any
additional costs necessary to such design, permitting and construction in excess
of the Final Costs shall, to the extent they exceed the remaining balance of the
Initial Allowance, be paid by Tenant to Landlord as an addition to the
Over-Allowance Amount within five (5) business days after Tenant's receipt of
invoice therefor from Landlord and, in any event, prior to the commencement of
the construction of such changes, or, at Landlord's option, Tenant shall make
payments for such additional costs out of its own funds, but Tenant shall
continue to provide Landlord with the documents described in Sections 2.2.2.1
(i), (ii), (iii) and (iv) above, for Landlord's approval, prior to Tenant paying
such costs.
 
4.2.2            Tenant's Agents.
 
4.2.2.1                   Landlord's General Conditions for Tenant's Agents and
Tenant Improvement Work.  Tenant's and Tenant's Agents' construction of the
Tenant Improvements shall comply with the following:  (i) the Tenant
Improvements shall be constructed in strict accordance with the Approved Working
Drawings; (ii) Tenant and Tenant's Agents shall not, in any way, interfere with,
obstruct, or delay, the work of Landlord's base building contractor and
subcontractors with respect to the Base, Shell and Core or any other work in the
Buildings or Project; (iii) Tenant's Agents shall submit schedules of all work
relating to the Tenant's Improvements to the Contractor and the Contractor
shall, within five (5) business days after Tenant's receipt thereof, inform
Tenant's Agents of any changes which are necessary thereto, and Tenant's Agents
shall adhere to such corrected schedule; and (iv) Tenant shall abide by all
rules made by Landlord's Building contractor or Landlord's Building manager with
respect to the use of freight, loading dock and service elevators, storage of
materials, coordination of work with the contractors of other tenants, and any
other matter in connection with this Tenant Work Letter, including, without
limitation, the construction of the Tenant Improvements.
 
4.2.2.2                   Coordination Fee.  Tenant shall pay a logistical
coordination fee (the "Coordination Fee") to Landlord in an amount equal to the
product of (i) five percent (5%), and (ii) the sum of the Initial Allowance, the
Over-Allowance Amount, as such amount may be increased hereunder, and any other
amounts expended by Tenant in connection with the design and construction of the
Tenant Improvements, which Coordination Fee shall be for services relating to
the coordination of the construction of the Tenant Improvements.
 
4.2.2.3                   Indemnity.  Tenant's indemnity of Landlord as set
forth in the Lease shall also apply with respect to any and all costs, losses,
damages, injuries and liabilities related in any way to any act or omission of
Tenant or Tenant's Agents, or anyone directly or indirectly employed by any of
them, or in connection with Tenant's non-payment of any amount arising out of
the Tenant Improvements and/or Tenant's disapproval of all or any portion of any
request for payment.  Such indemnity by Tenant, as set forth in the Lease, shall
also apply with respect to any and all costs, losses, damages, injuries and
liabilities related in any way to Landlord's performance of  any ministerial
acts reasonably necessary (i) to permit Tenant to complete the Tenant
Improvements, and (ii) to enable Tenant to obtain any building permit or
certificate of occupancy for the Premises.
 
4.2.2.4                   Insurance Requirements.
 
4.2.2.4.1  General Coverages.  All of Tenant's Agents shall carry worker's
compensation insurance covering all of their respective employees, and shall
also carry public liability insurance, including property damage, all with
limits, in form and with companies as are required to be carried by Tenant as
set forth in the Lease.
 
4.2.2.4.2 Special Coverages.  Tenant shall carry "Builder's All Risk" insurance
in an amount equal to the full replacement cost of the improvements being
constructed by Tenant, and such other insurance as Landlord may require, it
being understood and agreed that the Tenant Improvements shall be insured by
Tenant pursuant to the Lease immediately upon completion thereof.  Such
insurance shall be in amounts and shall include such extended coverage
endorsements as may be reasonably required by Landlord, and in form and with
companies as are required to be carried by Tenant as set forth in the Lease.
 
4.2.2.4.3  General Terms.  Certificates for all insurance carried pursuant to
this Section 4.2.2.4 shall be delivered to Landlord before the commencement of
construction of the Tenant Improvements and before the Contractor's equipment is
moved onto the site.  All such policies of insurance must contain a provision
that the company writing said policy will give Landlord thirty (30) days prior
written notice of any cancellation or lapse of the effective date or any
reduction in the amounts of such insurance.  If the Tenant Improvements are
damaged by any cause during the course of the construction thereof, Tenant shall
immediately repair the same at Tenant's sole cost and expense.  All policies
carried under this Section 4.2.2.4 shall insure Landlord and Tenant, as their
interests may appear, as well as the Contractor and Tenant's Agents, and shall
name as additional insureds Landlord's property manager, Landlord's asset
manager, and all mortgagees and ground lessors of the Buildings.  All insurance,
except Workers' Compensation, maintained by Tenant's Agents shall preclude
subrogation claims by the insurer against anyone insured thereunder.  Such
insurance shall provide that it is primary insurance as respects the owner and
that any other insurance maintained by owner is excess and noncontributing with
the insurance required hereunder.  The requirements for the foregoing insurance
shall not derogate from the provisions for indemnification of Landlord by Tenant
under Section 4.2.2.3 of this Tenant Work Letter.
 
 EXHIBIT B
-4-
MARINA VILLAGE
[Biotime]

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

4.2.3            Governmental Compliance.  The Tenant Improvements shall comply
in all respects with the following:  (i) the Code and other state, federal, city
or quasi-governmental laws, codes, ordinances and regulations (including,
without limitation, California Energy Code, Title 24), as each may apply
according to the rulings of the controlling public official, agent or other
person; (ii) applicable standards of the American Insurance Association
(formerly, the National Board of Fire Underwriters) and the National Electrical
Code; and (iii) building material manufacturer's specifications.
 
4.2.4            Inspection by Landlord.  Landlord shall have the right to
inspect the Tenant Improvements at all times, provided however, that Landlord's
failure to inspect the Tenant Improvements shall in no event constitute a waiver
of any of Landlord's rights hereunder nor shall Landlord's inspection of the
Tenant Improvements constitute Landlord's approval of the same.  Should Landlord
disapprove any portion of the Tenant Improvements, Landlord shall notify Tenant
in writing of such disapproval and shall specify the items disapproved.  Any
defects or deviations in, and/or disapproval by Landlord of, the Tenant
Improvements shall be rectified by Tenant at no expense to Landlord, provided
however, that if Landlord determines that a defect or deviation exists or
disapproves of any matter in connection with any portion of the Tenant
Improvements and such defect, deviation or matter might adversely affect the
mechanical, electrical, plumbing, HVAC or life-safety systems of the Buildings,
the structure or exterior appearance of the Buildings or any other tenant's use
of such other tenant's leased premises, Landlord may, take such action as
Landlord deems necessary, at Tenant's expense and without incurring any
liability on Landlord's part, to correct any such defect, deviation and/or
matter, including, without limitation, causing the cessation of performance of
the construction of the Tenant Improvements until such time as the defect,
deviation and/or matter is corrected to Landlord's satisfaction.
 
4.2.5            Meetings.  Commencing upon the execution of the Lease, Tenant
shall hold weekly meetings at a reasonable time, with the Architect and the
Contractor regarding the progress of the preparation of Construction Drawings
and the construction of the Tenant Improvements, which meetings shall be held at
a location designated by Landlord, and Landlord and/or its agents shall receive
prior notice of, and shall have the right to attend, all such meetings, and,
upon Landlord's request, certain of Tenant's Agents shall attend such meetings. 
In addition, minutes shall be taken at all such meetings, a copy of which
minutes shall be promptly delivered to Landlord.  One such meeting each month
shall include the review of the Contractor's current request for payment.
 
4.3           Notice of Completion; Copy of "As Built" Plans.  Within ten (10)
days after completion of construction of the Tenant Improvements, Tenant shall
cause a Notice of Completion to be recorded in the office of the Recorder of the
County in which the Buildings are located in accordance with Section 8182 of the
Civil Code of the State of California or any successor statute, and shall
furnish a copy thereof to Landlord upon such recordation.  If Tenant fails to do
so, Landlord may execute and file the same on behalf of Tenant as Tenant's agent
for such purpose, at Tenant's sole cost and expense.  At the conclusion of
construction, (i) Tenant shall cause the Architect and the Contractor (A) to
update the Approved Working Drawings as necessary to reflect all changes made to
the Approved Working Drawings during the course of construction, (B) to certify
to the best of their knowledge that the "record-set" of as-built drawings are
true and correct, which certification shall survive the expiration or
termination of the Lease, (C) to deliver to Landlord two (2) sets of sepias of
such as-built drawings within ninety (90) days following issuance of a
certificate of occupancy for the Premises, and (D) to deliver to Landlord a
computer disk containing the Approved Working Drawings in AutoCAD format, and
(ii) Tenant shall deliver to Landlord a copy of all warranties, guaranties, and
operating manuals and information relating to the improvements, equipment, and
systems in the Premises.
 
4.4           Coordination by Tenant's Agents with Landlord.  Upon Tenant's
delivery of the Contract to Landlord under Section 4.2.1 of this Tenant Work
Letter, Tenant shall furnish Landlord with a schedule setting forth the
projected date of the completion of the Tenant Improvements and showing the
critical time deadlines for each phase, item or trade relating to the
construction of the Tenant Improvements.
 
SECTION 5

MISCELLANEOUS
 
5.1           Tenant's Representative.  Tenant has designated Floyd Kastning as
its sole representative with respect to the matters set forth in this Tenant
Work Letter, who shall have full authority and responsibility to act on behalf
of the Tenant as required in this Tenant Work Letter.
 
5.2           Landlord's Representative.  Landlord has designated Melanie
Guevara as its sole representative with respect to the matters set forth in this
Tenant Work Letter, who, until further notice to Tenant, shall have full
authority and responsibility to act on behalf of the Landlord as required in
this Tenant Work Letter.
 
5.3           Time of the Essence in This Tenant Work Letter.  Unless otherwise
indicated, all references herein to a "number of days" shall mean and refer to
calendar days.  If any item requiring approval is timely disapproved by
Landlord, the procedure for preparation of the document and approval thereof
shall be repeated until the document is approved by Landlord.
 
 EXHIBIT B
-5-
MARINA VILLAGE
[Biotime]

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

5.4           Tenant's Lease Default.  Notwithstanding any provision to the
contrary contained in the Lease, if an event of default by Tenant of this Tenant
Work Letter or the Lease has occurred at any time on or before the substantial
completion of the Premises, then (i) in addition to all other rights and
remedies granted to Landlord pursuant to the Lease, at law and/or in equity,
Landlord shall have the right to withhold payment of all or any portion of the
Tenant Improvement Allowance and/or Landlord may cause the Contractor to cease
the construction of the Tenant Improvements (in which case, Tenant shall be
responsible for any delay in the substantial completion of the Premises caused
by such work stoppage), and (ii) all other obligations of Landlord under the
terms of this Tenant Work Letter shall be forgiven until such time as such
default is cured pursuant to the terms of the Lease  (in which case, Tenant
shall be responsible for any delay in the substantial completion of the Premises
caused by such inaction by Landlord).  In addition, if the Lease is terminated
prior to the Lease Commencement Date due to a default by Tenant as described in
Section 19.1 of the Lease or under this Tenant Work Letter, in addition to any
other remedies available to Landlord under the Lease, at law and/or in equity,
Tenant shall pay to Landlord, as Additional Rent under the Lease, within five
(5) business days after Tenant's receipt of a statement therefor, any and all
costs (if any) incurred by Landlord (including any portion of the Tenant
Improvement Allowance disbursed by Landlord) and not reimbursed or otherwise
paid by Tenant through the date of such termination in connection with the
Tenant Improvements to the extent planned, installed and/or constructed as of
such date of termination, including, but not limited to, any costs related to
the removal of all or any portion of the Tenant Improvements and restoration
costs related thereto.
 
 EXHIBIT B
-6-
MARINA VILLAGE
[Biotime]

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

EXHIBIT C
 
AMENDMENT TO LEASE
 
This AMENDMENT TO LEASE ("Amendment") is made and entered into effective as of
_________________, 20__, by and between BSREP MARINA VILLAGE OWNER LLC, a
Delaware limited liability company ("Landlord") and BIOTIME, INC., a California
corporation ("Tenant").
 
R E C I T A L S :
 
A.            Landlord and Tenant entered into that certain Lease dated as of
December __, 2015 (the "Lease") pursuant to which Landlord leased to Tenant and
Tenant leased from Landlord certain "Premises", as described in the Lease, in
those certain buildings located at 1010 Atlantic Avenue and 1020 Atlantic
Avenue, Alameda, California  94501.
 
B.             Except as otherwise set forth herein, all capitalized terms used
in this Amendment shall have the same meaning as such terms have in the Lease.
 
C.             Landlord and Tenant desire to amend the Lease to confirm the
commencement and expiration dates of the term, as hereinafter provided.
 
NOW, THEREFORE, in consideration of the foregoing Recitals and the mutual
covenants contained herein, and for other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:
 
1.             Confirmation of Dates.  The parties hereby confirm that (a) the
Premises are Ready for Occupancy, and (b) the term of the Lease commenced as of
____________________ for a term of seven (7) years ending on
_______________________ (unless sooner terminated as provided in the Lease).
 
2.             No Further Modification.  Except as set forth in this Amendment,
all of the terms and provisions of the Lease shall remain unmodified and in full
force and effect.
 
IN WITNESS WHEREOF, this Amendment has been executed as of the day and year
first above written.
 

 
"Landlord":
           
BSREP MARINA VILLAGE OWNER LLC,
 
a Delaware limited liability company
     
By:
         
Name:   Thomas Diamond
   
Its:   Vice President
 

 

 
"Tenant":
           
BIOTIME, INC.,
 
a California corporation
     
By:
          
Name: 
          
Its:
        

 

 
By:
      
   
Name:  
           
 
Its: 
         

 
 EXHIBIT C
-1-
MARINA VILLAGE
[Biotime]

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

EXHIBIT D
 
RULES AND REGULATIONS
 
Tenant shall faithfully observe and comply with the following Rules and
Regulations and the Parking Rules and Regulations.  Landlord shall not be
responsible to Tenant for the nonperformance of any of said Rules and
Regulations and/or the Parking Rules and Regulations by or otherwise with
respect to the acts or omissions of any other tenants or occupants of the
Buildings and/or the Project, provided that Landlord shall use commercially
reasonable efforts (but not including the institution of legal proceedings) to
cause such tenants and occupants to comply with such Rules and Regulations to
the extent such non-compliance material, adversely affects Tenant's access to or
use of the Premises for Tenant's Permitted Use.  In the event of conflict
between the Rules and Regulations and/or the Parking Rules and Regulations and
any modifications thereto and the terms of the Lease, the Lease shall control.
 
1.             Tenant shall not place any lock(s) on any door, or install any
security system (including, without limitation, card key systems, alarms or
security cameras), in the Premises without Landlord's prior written consent,
which consent shall not be unreasonably withheld, and Landlord shall have the
right to retain at all times and to use keys or other access codes or devices to
all locks and/or security systems within and to the Premises.  A reasonable
number of keys to the locks on the entry doors of the Premises shall be
furnished by Landlord to Tenant at Tenant's cost, and Tenant shall not make any
duplicate keys.  All keys shall be returned to Landlord at the expiration or
earlier termination of the Lease.  Further, if and to the extent Tenant re-keys,
re-programs or otherwise changes any locks in or for the Premises, all such
locks and key systems must be consistent with the master lock and key system at
the Buildings, all at Tenant's sole cost and expense.
 
2.             All doors opening to public corridors shall be kept closed at all
times except for normal ingress and egress to the Premises, unless electrical
hold backs have been installed.  Sidewalks, doorways, passages, entrances,
vestibules, halls, stairways and other Common Areas shall not be obstructed by
Tenant or used by Tenant for any purpose other than ingress and egress to and
from the Premises, and Tenant, its employees and agents shall not loiter in the
entrances or corridors.
 
3.              Landlord reserves the right to close and keep locked all
entrance and exit doors of the Buildings during such hours as are customary for
the Comparable Buildings.  Tenant and its employees and agents shall ensure that
the doors to the Buildings are securely closed and locked when leaving the
Premises if it is after the normal hours of business for the Buildings.  Any
tenant, its employees, agents or any other persons entering or leaving the
Buildings at any time when it is so locked, or any time when it is considered to
be after normal business hours for the Buildings, may be required to sign the
applicable Building register when so doing.  After-hours access by Tenant’s
authorized employees and contractors shall be permitted and may be provided by
hard-key, card-key access or other procedures adopted by Landlord from time to
time; Tenant shall pay for the costs of all access cards provided to Tenant’s
employees and all replacements thereof for lost, stolen and/or damaged cards. 
Access to the Buildings and/or the Project may be refused unless the person
seeking access has proper identification or has a previously arranged pass for
such access.  Landlord and its agents shall in no case be liable for damages for
any error with regard to the admission to or exclusion from the Buildings and/or
the Project of any person.  In case of invasion, mob, riot, public excitement,
or other commotion, Landlord reserves the right to prevent access to the
Buildings and/or the Project during the continuance of same by any means it
deems appropriate for the safety and protection of life and property.
 
4.             Landlord shall have the right to prescribe the weight, size and
position of all safes and other heavy property brought into the Buildings. 
Safes and other heavy objects shall, if considered necessary by Landlord, stand
on supports of such thickness as is necessary to properly distribute the
weight.  Landlord will not be responsible for loss of or damage to any such safe
or property in any case.  All damage done to any part of the Buildings, their
contents, occupants and/or visitors by moving or maintaining any such safe or
other property shall be the sole responsibility of Tenant and any expense of
said damage or injury shall be borne by Tenant.
 
5.              No furniture, freight, packages, supplies, equipment or
merchandise will be brought into or removed from the Buildings or carried up or
down in the elevators, except upon prior notice to Landlord, and in such manner,
in such specific elevator, and between such hours as shall be designated by
Landlord.  Tenant shall provide Landlord with not less than 24 hours' prior
notice of the need to utilize an elevator for any such purpose, so as to provide
Landlord with a reasonable period to schedule such use and to install such
padding or take such other actions or prescribe such procedures as are
appropriate to protect against damage to the elevators or other parts of the
Buildings.  Tenant shall assume all risk for damage to articles moved and injury
to any persons resulting from such activity described herein.  If equipment,
property, or personnel of Landlord or of any other party is damaged or injured
as a result of or in connection with such activity described herein, Tenant
shall be solely liable for any resulting damage or loss.
 
6.              Landlord shall have the right to control and operate the public
portions of the Buildings and Project, the public facilities, the heating and
air conditioning, and any other facilities furnished for the common use of
tenants, in such manner as is customary for the Comparable Buildings.
 
7.              No signs, advertisements or notices shall be painted or affixed
to windows, doors or other parts of the Buildings, except those of such color,
size, style and in such places as are first approved in writing by Landlord. 
Landlord shall have the right to remove any signs, advertisements, and notices
not approved in writing by Landlord without notice to and at the expense of
Tenant.  Landlord may provide and maintain in the first floor (main lobby) of
the Buildings an alphabetical directory board or other directory device listing
tenants, and no other directory shall be permitted unless previously consented
to by Landlord in writing.
 
 EXHIBIT D
-1-
MARINA VILLAGE
[Biotime]

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

8.             The requirements of Tenant will be attended to only upon
application at the management office of the Project or at such office location
designated by Landlord.
 
9.             Tenant shall not disturb (by use of any television, radio or
musical instrument, making loud or disruptive noises, creating offensive odors
or otherwise), solicit, or canvass any occupant of the Buildings and/or the
Project and shall cooperate with Landlord or Landlord’s agents to prevent same.
 
10.          The toilet rooms, urinals, wash bowls and other apparatus shall not
be used for any purpose other than that for which they were constructed, and no
foreign substance of any kind whatsoever shall be thrown therein.  The expense
of any breakage, stoppage or damage resulting from the violation of this rule
shall be borne by the tenant who, or whose employees or invitees, shall have
caused it.
 
11.          Tenant shall not overload the floor of the Premises.  Tenant shall
not mark, drive nails or screws, or drill into the partitions, woodwork or
plaster or in any way deface the Premises or any part thereof without Landlord’s
consent first having been obtained; provided, however, Landlord’s prior consent
shall not be required with respect to Tenant’s placement of pictures and other
normal office wall hangings on the interior walls of the Premises (but at the
end of the Lease Term, Tenant shall repair any holes and other damage to the
Premises resulting therefrom).
 
12.          Except for vending machines intended for the sole use of Tenant’s
employees and invitees, no vending machine or machines of any description other
than fractional horsepower office machines shall be installed, maintained or
operated upon the Premises without the written consent of Landlord.  Tenant
shall not install, operate or maintain in the Premises or in any other area of
the Buildings, electrical equipment that would overload the electrical system
beyond its capacity for proper, efficient and safe operation as determined
solely by Landlord.
 
13.          Tenant shall not use any method of heating or air conditioning
other than that which may be supplied by Landlord, without the prior written
consent of Landlord.  Tenant shall not furnish cooling or heating to the
Premises, including, without limitation, the use of electronic or gas heating
devices, portable coolers (such as "move n cools") or space heaters, without
Landlord's prior written consent, and any such approval will be for devices that
meet federal, state and local code.
 
14.          No inflammable, explosive or dangerous fluids or substances shall
be used or kept by Tenant in the Premises, Buildings and/or about the Project,
except for those approved by Landlord pursuant to Section 5.2 of the Lease
and/or substances as are typically found in similar premises used for general
office purposes and are being used by Tenant in a safe manner and in accordance
with all Applicable Laws, rules and regulations.
 
15.          Tenant shall not use, keep or permit to be used or kept, any foul
or noxious gas or substance in or on the Premises which unreasonably disturbs
other occupants of the Buildings, or permit or allow the Premises to be occupied
or used in a manner offensive or objectionable to Landlord or other occupants of
the Buildings and/or the Project by reason of noise, odors, or vibrations, or
interfere in any way with other tenants or those having business therewith.
 
16.          Tenant shall not bring into or keep within the Project, the
Buildings or the Premises any animals (except those assisting handicapped
persons), birds, fish tanks, bicycles or other vehicles.
 
17.          Tenant shall not use, or permit any part of the Premises to be
used, for lodging, sleeping or for any illegal purpose.
 
18.          No cooking shall be done or permitted by Tenant on the Premises. 
Notwithstanding the foregoing, Underwriters’ laboratory-approved equipment and
microwave ovens may be used in the Premises for heating food and brewing coffee,
tea, hot chocolate and similar beverages, provided that such use is in
accordance with all Applicable Laws, and does not cause odors which are
objectionable to Landlord and other tenants.
 
19.          Landlord will approve where and how telephone and telegraph wires
and other cabling are to be introduced to the Premises.  No boring or cutting
for wires outside the Premises shall be allowed without the consent of Landlord
(Tenant shall be permitted to install wiring inside the Premises without
Landlord's consent, but otherwise in accordance with Article 8 of the Lease or
the Tenant Work Letter, provided such wiring does not affect the base, shell and
core of the Building and/or the Systems and Equipment).  The location of
telephone, call boxes and other office equipment and/or systems affixed to the
Premises shall be subject to the approval of Landlord.  Tenant shall not use
more than its proportionate share of telephone lines and other telecommunication
facilities available to service the Buildings.
 
20.          Landlord reserves the right to exclude or expel from the Buildings
and/or the Project any person who, in the judgment of Landlord, is intoxicated
or under the influence of liquor or drugs, or who shall in any manner do any act
in violation of any of these Rules and Regulations or cause harm to Building
occupants and/or property.
 
21.          All contractors, contractor's representatives and installation
technicians performing work in the Buildings or at the Project shall be subject
to Landlord's prior approval, which approval shall not be unreasonably withheld,
and shall be required to comply with Landlord's standard rules, regulations,
policies and procedures, which may be revised from time to time.
 
22.          Intentionally deleted.
 
23.          Tenant at all times shall maintain the entire Premises in a neat
and clean, first class condition, free of debris.  Tenant shall not place items,
including, without limitation, any boxes, files, trash receptacles or loose
cabling or wiring, in or near any window to the Premises which would be visible
anywhere from the exterior of the Premises.
 
 EXHIBIT D
-2-
MARINA VILLAGE
[Biotime]

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

24.          Tenant shall not waste electricity, water or air conditioning and
agrees to cooperate fully with Landlord to ensure the most effective operation
of the Buildings’ heating and air conditioning systems, including, without
limitation, the use of window blinds to block solar heat load, and shall refrain
from attempting to adjust any controls.  Tenant shall comply with and
participate in any program for metering or otherwise measuring the use of
utilities and services, including, without limitation, programs requiring the
disclosure or reporting of the use of any utilities or services.  Tenant shall
also cooperate and comply with, participate in, and assist in the implementation
of (and take no action that is inconsistent with, or which would result in
Landlord, the Buildings and/or the Project failing to comply with the
requirements of) any conservation, sustainability, recycling, energy efficiency,
and waste reduction programs, environmental protection efforts and/or other
programs that are in place and/or implemented from time to time at the Buildings
and/or the Project, including, without limitation, any required reporting,
disclosure, rating or compliance system or program (including, but not limited
to, any LEED [Leadership in Energy and Environmental Design] rating or
compliance system, including those currently coordinated through the U.S. Green
Building Council).
 
25.          Tenant shall store all its recyclables, trash and garbage within
the interior of the Premises.  No material shall be placed in the trash boxes or
receptacles if such material is of such nature that it may not be disposed of in
the ordinary and customary manner of removing and disposing of recyclables,
trash and garbage in the city in which the Project is located without violation
of any law or ordinance governing such disposal.  All trash, garbage and refuse
disposal shall be made only through entry-ways and elevators provided for such
purposes at such times as Landlord shall designate.
 
26.          Tenant shall comply with all safety, fire protection and evacuation
procedures and regulations established by Landlord or any governmental agency.
 
27.          Tenant shall assume any and all responsibility for protecting the
Premises from theft, robbery and pilferage, which includes keeping doors locked
and other means of entry to the Premises closed, when the Premises are not
occupied, or when the entry to the Premises is not manned by Tenant on a regular
basis.
 
28.          No awnings or other projection shall be attached to the outside
walls of the Buildings without the prior written consent of Landlord.  No
curtains, blinds, shades or screens shall be attached to or hung in, or used in
connection with, any window or door of the Premises that are visible from
outside the Premises without the prior written consent of Landlord.  The sashes,
sash doors, skylights, windows, and doors that reflect or admit light and air
into the halls, passageways or other public places in the Buildings shall not be
covered or obstructed by Tenant, nor shall any bottles, parcels or other
articles be placed on the windowsills.  All electrical ceiling fixtures hung in
offices or spaces along the perimeter of the Buildings must be fluorescent
and/or of a quality, type, design and bulb color approved by Landlord.
 
29.          The washing and/or detailing of or, the installation of
windshields, radios, telephones in or general work on, automobiles shall not be
allowed on the Project, except under specific arrangement with Landlord.
 
30.          Food vendors shall be allowed in the Buildings upon receipt of a
written request from Tenant delivered to Landlord.  The food vendor shall
service only the tenants that have a written request on file in the management
office of the Project.  Under no circumstance shall the food vendor display
their products in a public or Common Area including corridors and elevator
lobbies.  Any failure to comply with this rule shall result in immediate
permanent withdrawal of the vendor from the Buildings.  Tenant shall obtain ice,
drinking water, linen, barbering, shoe polishing, floor polishing, cleaning,
janitorial, plant care or other similar services only from vendors who have
registered in the management office of the Project and who have been approved by
Landlord for provision of such services in the Premises.
 
31.          Tenant must comply with requests by the Landlord concerning the
informing of their employees of items of importance to the Landlord.
 
32.          Tenant shall comply with any non-smoking ordinance adopted by any
applicable governmental authority.  Neither Tenant nor its agents, employees,
contractors, guests or invitees shall smoke or permit smoking in the Premises
and/or the Common Areas, unless the Common Areas have been declared a designated
smoking area by Landlord, nor shall the above parties allow smoke from the
Premises to emanate into the Common Areas or any other part of the Buildings. 
Landlord shall have the right to designate the Buildings (including the
Premises) as non-smoking buildings.
 
33.          Tenant shall not take any action which would violate Landlord's
labor contracts or which would cause a work stoppage, picketing, labor
disruption or dispute, or interfere with Landlord's or any other tenant's or
occupant's business or with the rights and privileges of any person lawfully in
the Buildings ("Labor Disruption").  Tenant shall take the actions necessary to
resolve the Labor Disruption, and shall have pickets removed and, at the request
of Landlord, immediately terminate any work in the Premises that gave rise to
the Labor Disruption, until Landlord gives its written consent for the work to
resume, and Tenant shall have no claim for damages against Landlord or any of
its trustees, members, principals, beneficiaries, partners, officers, directors,
employees, mortgagees, or agents in connection therewith.
 
34.           No tents, shacks, temporary or permanent structures of any kind
shall be allowed on the Project.  No personal belongings may be left unattended
in any Common Areas.
 
 EXHIBIT D
-3-
MARINA VILLAGE
[Biotime]

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

35.          Landlord shall have the right to prohibit the use of the name of
the Buildings or Project or any other publicity by Tenant that in Landlord's
sole opinion may impair the reputation of the Buildings or Project or the
desirability thereof.  Upon written notice from Landlord, Tenant shall refrain
from and discontinue such publicity immediately.
 
36.          Landlord shall have the right to designate and approve standard
window coverings for the Premises and to establish rules to assure that the
Buildings present a uniform exterior appearance.  Tenant shall ensure, to the
extent reasonably practicable, that window coverings are closed on windows in
the Premises while they are exposed to the direct rays of the sun.
 
37.          The work of cleaning personnel shall not be hindered by Tenant
after 5:30 P.M., and cleaning work may be done at any time when the offices are
vacant.  Windows, doors and fixtures may be cleaned at any time.  Tenant shall
provide adequate waste and rubbish receptacles to prevent unreasonable hardship
to the cleaning service.
 
38.          Tenant shall comply with all Building security procedures as
Landlord may effectuate.
 
39.          Tenant shall at all times cooperate with Landlord in preserving a
first-class image for the Buildings.
 
PARKING RULES AND REGULATIONS
 
1.             Landlord reserves the right to establish and reasonably change
the hours for the Parking Facilities, on a non-discriminatory basis, from time
to time.  Notwithstanding the foregoing, Tenant and its employees shall have
access to the Parking Facilities 24 hours per day, 365 days per year, including
holidays, subject to the terms and conditions in the Lease.  Tenant shall not
store or permit its employees to store any automobiles in the Parking Facilities
without the prior written consent of Landlord (and/or the Parking Operator, as
the case may be).  Except for emergency repairs, Tenant and its employees shall
not perform any work on any automobiles while located in the Parking Facilities
or on the Project.  The Parking Facilities may not be used by Tenant or its
agents for overnight parking of vehicles.  If it is necessary for Tenant or its
employees to leave an automobile in the Parking Facilities overnight, Tenant
shall provide Landlord (or the Parking Operator as the case may be) with prior
notice thereof designating the license plate number and model of such
automobile.
 
2.             Tenant (including Tenant's employees and agents) will use the
parking spaces solely for the purpose of parking passenger model cars, small
vans and small trucks and will comply in all respects with any rules and
regulations that may be promulgated by Landlord and/or the Parking Operator from
time to time with respect to the Parking Facilities.
 
3.             Vehicles must be parked entirely within the stall lines painted
on the floor, and only small cars may be parked in areas reserved for small
cars.
 
4.             All directional signs and arrows must be observed.
 
5.             The speed limit shall be 5 miles per hour.
 
6.             Parking spaces reserved for handicapped persons must be used only
by vehicles properly designated.
 
7.             Parking is prohibited in all areas not expressly designated for
parking, including without limitation:
 
(a)           areas not striped for parking;
(b)          aisles;
(c)           where "no parking" signs are posted;
(d)           ramps; and
(e)           loading zones.
 
8.             Parking stickers, key cards and any other devices or forms of
identification or entry supplied by Landlord or the Parking Operator shall
remain the property of Landlord (or the Parking Operator as the case may be). 
Such device must be displayed as requested and may not be mutilated in any
manner.  The serial number of the parking identification device may not be
obliterated.  Parking passes and devices are not transferable and any pass or
device in the possession of an unauthorized holder will be void.
 
9.             Parking managers or attendants are not authorized to make or
allow any exceptions to these Parking Rules and Regulations.
 
10.          Every parker is required to park and lock his/her own car.
 
11.          Loss or theft of parking passes, identification, key cards or other
such devices must be reported to Landlord (and/or to the Parking Operator as the
case may be) immediately.  Any parking devices reported lost or stolen found on
any authorized car will be confiscated and the illegal holder will be subject to
prosecution.  Lost or stolen passes and devices found by Tenant or its employees
must be reported to Landlord (and to the Parking Operator, as the case may be)
immediately.
 
12.          Washing, waxing, cleaning or servicing of any vehicle by the
customer and/or its agents is prohibited.
 
 EXHIBIT D
-4-
MARINA VILLAGE
[Biotime]

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

13.          Tenant agrees to acquaint all persons to whom Tenant assigns a
parking space with these Parking Rules and Regulations.
 
14.          Landlord shall not be liable for loss of or damage to any vehicle
or any contents of such vehicle or accessories to any such vehicle, or any
property left in any of the Parking Facilities, resulting from fire, theft,
vandalism, accident, conduct of other users of the Parking Facilities and other
persons, or any other casualty or cause; provided, however, Landlord shall
indemnify Tenant for any Claims resulting from the negligence or willful
misconduct of Landlord and/or the Landlord Parties and not insured or required
to be insured by Tenant under the Lease (but in no event shall Landlord be
liable for Consequential Damages).  Further, Tenant understands and agrees
that:  (i) Landlord will not be obligated to provide any traffic control,
security protection or Parking Operator for the Parking Facilities; (ii) Tenant
uses the Parking Facilities at its own risk; and (iii) Landlord will not be
liable for personal injury or death, or theft, loss of or damage to property. 
Tenant indemnifies and agrees to hold Landlord and its respective agents and
employees harmless from and against any and all claims, demands, and actions
arising out of the use of the Parking Facilities by Tenant and its employees and
agents, whether brought by any of such persons or any other person, except to
the extent caused by Landlord's gross negligence or willful misconduct and not
insured or required to be insured by Tenant under the Lease.
 
15.          Tenant will ensure that any vehicle parked in any of the parking
spaces will be kept in proper repair and will not leak excessive amounts of oil
or grease or any amount of gasoline.  If any of the parking spaces are at any
time used (i) for any purpose other than parking as provided above, (ii) in any
way or manner reasonably objectionable to Landlord, or (iii) by Tenant after
default by Tenant under the Lease, Landlord, in addition to any other rights
otherwise available to Landlord, may consider such default an event of default
under the Lease.
 
16.          Tenant's right to use the Parking Facilities will be in common with
other tenants of the Project and with other parties permitted by Landlord to use
the Parking Facilities.  Landlord reserves the right to assign and reassign,
from time to time, particular parking spaces for use by persons selected by
Landlord, provided that Tenant's rights under the Lease are preserved.  Landlord
will not be liable to Tenant for any unavailability of Tenant's designated
spaces, if any, nor will any unavailability entitle Tenant to any refund,
deduction, or allowance.  Tenant will not park in any numbered space or any
space designated as:  RESERVED, HANDICAPPED, VISITORS ONLY, or LIMITED TIME
PARKING (or similar designation).
 
17.          If the Parking Facilities are damaged or destroyed, or if the use
of the Parking Facilities is limited or prohibited by any governmental
authority, or the use or operation of the Parking Facilities is limited or
prevented by strikes or other labor difficulties or other causes beyond
Landlord's reasonable control, Tenant's inability to use the parking spaces will
not subject Landlord (and/or the Parking Operator, as the case may be) to any
liability to Tenant and will not relieve Tenant of any of its obligations under
the Lease and the Lease will remain in full force and effect.  Tenant will pay
to Landlord upon demand, and Tenant indemnifies Landlord against, any and all
loss or damage to the Parking Facilities, or any equipment, fixtures, or signs
used in connection with the Parking Facilities and any adjoining buildings or
structures caused by Tenant or any of its employees and agents.
 
18.          Tenant has no right to assign or sublicense any of its rights in
the parking passes, except as part of a permitted assignment or sublease of the
Lease; however, Tenant may allocate the parking passes among its employees.
 
Tenant shall be responsible for the observance of all of the Rules and
Regulations and Parking Rules and Regulations in this Exhibit D by Tenant’s
employees, agents, clients, customers, invitees and guests.  Landlord may waive
any one or more of the Rules and Regulations and/or Parking Rules and
Regulations for the benefit of any particular tenant or tenants, but no such
waiver by Landlord shall be construed as a waiver of such Rules and Regulations
and/or Parking Rules and Regulations in favor of any other tenant or tenants,
nor prevent Landlord from thereafter enforcing any such Rules or Regulations
and/or Parking Rules and Regulations against any or all tenants of the Buildings
and/or the Project.  Landlord reserves the right at any time to change or
rescind any one or more of these Rules and Regulations and/or the Parking Rules
and Regulations, or to make such other and further reasonable non-discriminatory
Rules and Regulations and/or Parking Rules and Regulations as in Landlord’s
judgment may from time to time be necessary for the management, safety, care and
cleanliness of the Premises, Buildings and Project, and for the preservation of
good order therein, as well as for the convenience of other occupants and
tenants therein provided that Landlord shall use commercially reasonable efforts
(but not including the institution of legal proceedings) to cause such tenants
and occupants to comply with such Rules and Regulations to the extent such
non-compliance material, adversely affects Tenant's access to or use of the
Premises for Tenant's Permitted Use.  Tenant shall be deemed to have read these
Rules and Regulations and Parking Rules and Regulations and to have agreed to
abide by them subject to its rights under the Lease.
 
 EXHIBIT D
-5-
MARINA VILLAGE
[Biotime]

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

EXHIBIT E
 
DEPICTION OF GENERATOR SITE
 
[image4.jpg]
 
 
 EXHIBIT E
-1-
MARINA VILLAGE
[Biotime]

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

EXTENSION OPTION RIDER
 
This Extension Option Rider ("Extension Rider") is attached to and made a part
of the Lease by and between Landlord and Tenant.  The agreements set forth in
this Extension Rider shall have the same force and effect as if set forth in the
Lease.  To the extent the terms of this Extension Rider are inconsistent with
the terms of the Lease, the terms of this Extension Rider shall control.
 
1.              Extension Option.  Landlord hereby grants Tenant one (1) option
(the "Extension Option") to extend the Lease Term for a period of five (5) years
(the "Option Term"), which option shall be exercisable only by written Exercise
Notice (as defined below) delivered by Tenant to Landlord as provided below. 
Upon the proper exercise of the Extension Option, the Lease Term shall be
extended for the Option Term.  Notwithstanding the foregoing, at Landlord's
option, in addition to any other remedies available to Landlord under the Lease,
at law or in equity, the Extension Option shall not be deemed properly exercised
if as of the date of delivery of the Exercise Notice (as defined below) by
Tenant:  (i) Tenant has previously been in default under the Lease beyond all
applicable notice and cure periods; and/or (ii) Landlord does not approve of
Tenant's then-existing financial condition and/or Landlord's lender does not
approve of the terms for the Option Term, including, without limitation, the
Option Rent (as defined below).  The Extension Option is personal to the
Original Tenant and any Affiliate Assignee and may only be exercised by the
Original Tenant or such Affiliate Assignee (and not any other assignee,
sublessee or other transferee of Tenant's interest in the Lease or the Premises)
if the Original Tenant or such Affiliate Assignee, as the case may be, occupies
the entire Premises as of the date of Tenant's delivery of the Exercise Notice.
 
2.              Option Rent.  The annual Base Rent payable by Tenant during the
Option Term (the "Option Rent") shall be equal to the Fair Market Rental Rate
for the Premises.  As used herein, the "Fair Market Rental Rate" shall mean the
annual base rent at which tenants, as of the commencement of the Option Term,
will be leasing non-sublease space comparable in size, location and quality to
the Premises for a comparable term as the Option Term, which comparable space is
located in the Buildings, the Other Existing Buildings in the Project which are
office and R&D buildings, and in other comparable first-class office and R&D
buildings in the East Bay Office Market (collectively, the "Comparable
Buildings"), taking into consideration all free rent and other out-of-pocket
concessions generally being granted at such time for such comparable space for
the Option Term (including, without limitation, any tenant improvement allowance
provided for such comparable space, with the amount of such tenant improvement
allowance to be provided for the Premises during the Option Term to be
determined after taking into account the age, quality and layout of the tenant
improvements in the Premises as of the commencement of the Option Term with
consideration given to the fact that the improvements existing in the Premises
are specifically suitable to Tenant).  All other terms and conditions of the
Lease shall apply throughout the Option Term; however, Tenant shall, in no
event, have the option to extend the Lease Term beyond the Option Term described
in Section 1 above.
 
3.              Exercise of Option.  The Extension Option shall be exercised by
Tenant, if at all, only in the following manner:  (i) Tenant shall deliver
written notice ("Interest Notice") to Landlord not more than nine (9) months nor
less than eight (8) months prior to the expiration of the initial Lease Term
stating that Tenant may be interested in exercising the Extension Option; (ii)
Landlord, after receipt of Tenant's notice, shall deliver notice (the "Option
Rent Notice") to Tenant not less than seven (7) months prior to the expiration
of the initial Lease Term setting forth the Option Rent; and (iii) if Tenant
wishes to exercise the Extension Option, Tenant shall, on or before the date
(the "Exercise Date") which is six (6) months prior to the expiration of the
initial Lease Term, exercise the Extension Option by delivering written notice
("Exercise Notice") thereof to Landlord.  Concurrently with Tenant's delivery of
the Exercise Notice, Tenant may object, in writing, to Landlord's determination
of the Fair Market Rental Rate for the Option Term set forth in the Option Rent
Notice , in which event the Fair Market Rental Rate shall be determined pursuant
to Section 4 below.  If Tenant timely delivers the Exercise Notice but fails to
timely object in writing to Landlord's determination of the Fair Market Rental
Rate for the Option Term set forth in the Option Rent Notice, then Tenant shall
be deemed to have accepted Landlord's determination thereof and the following
provisions of Section 4 shall not apply.  Tenant's failure to deliver the
Interest Notice or Exercise Notice on or before the applicable delivery dates
therefor specified hereinabove shall be deemed to constitute Tenant's waiver of
the Extension Option.
 
4.             Determination of Option Rent.  If Tenant timely and appropriately
objects in writing pursuant to Section 3 above with respect to the Fair Market
Rental Rate for the Premises for the Option Term initially determined by
Landlord in Landlord's Option Rent Notice, then Landlord and Tenant shall
attempt to agree upon such Fair Market Rental Rate, using their best good-faith
efforts.  If Landlord and Tenant fail to reach agreement by the date (the
"Outside Agreement Date") which is twenty (20) days following Tenant's delivery
of the Exercise Notice, then each party shall submit to the other party a
separate written determination of the Fair Market Rental Rate for the Option
Term within ten (10) business days after the Outside Agreement Date, and such
determinations shall be submitted to arbitration in accordance with the
provisions of Sections 4.1 through 4.7 below.  The failure of Tenant or Landlord
to submit a written determination of the Fair Market Rental Rate within such ten
(10) business day period shall conclusively be deemed to be such party's
approval of the Fair Market Rental Rate submitted within such ten (10) business
day period by the other party.
 
4.1                 Landlord and Tenant shall each appoint one (1) arbitrator
who shall by profession be a real estate leasing broker who shall (i) have been
active over the ten (10) year period ending on the date of such appointment in
the leasing of the Buildings, the Other Existing Buildings which are office and
R&D buildings and the Comparable Buildings, (ii) have no financial interest in
Landlord or Tenant, and (iii) not have represented or been employed or engaged
by the appointing party during such 10-year period.  The determination of the
arbitrators shall be limited solely to the issue of whether Landlord's or
Tenant's submitted Fair Market Rental Rate for the Option Term is the closer to
the actual Fair Market Rental Rate therefor as determined by the arbitrators,
taking into account the requirements with respect thereto set forth in Section 2
above.  Each such arbitrator shall be appointed within fifteen (15) days after
the Outside Agreement Date.
 

-1-
MARINA VILLAGE
[Biotime]

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

4.2                 The two (2) arbitrators so appointed shall, within fifteen
(15) days of the date of the appointment of the last appointed arbitrator, agree
upon and appoint a third arbitrator who shall be qualified under the same
criteria set forth hereinabove for qualification of the initial two (2)
arbitrators.
 
4.3                The three (3) arbitrators shall, within thirty (30) days of
the appointment of the third arbitrator, reach a decision as to which of
Landlord's or Tenant's submitted Fair Market Rental Rate for the Option Term is
closer to the actual Fair Market Rental Rate therefor and shall select such
closer determination as the Fair Market Rental Rate therefor and notify Landlord
and Tenant thereof.
 
4.4                 The decision of the majority of the three (3) arbitrators
shall be binding upon Landlord and Tenant.
 
4.5                 If either Landlord or Tenant fails to appoint an arbitrator
within the time period specified in Section 4.1 hereinabove, the arbitrator
appointed by one of them shall reach the decision described in Section 4.3
above, notify Landlord and Tenant thereof, and such arbitrator's decision shall
be binding upon Landlord and Tenant.
 
4.6                 If the two (2) arbitrators fail to agree upon and appoint a
third arbitrator, a third arbitrator shall be appointed by the Superior Court in
and for the county of in which the Project is located.
 
4.7                 Each party shall pay the fees and expenses of the arbitrator
appointed by or on behalf of it, and each shall pay one-half of the fees and
expenses of the third arbitrator, if any.
 
 

-2-
MARINA VILLAGE
[Biotime]

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