Document:

<PAGE>

                                                                   EXHIBIT 10.13

Prepared By: Lessee:                                   Lessee:

         University of Tennessee                       Tristar Enterprises, Inc.
         Office of Real Estate Management              3 N. Dunlap Street
         The Middlebrook Building                      Memphis, TN 38 I63
         5723 Middlebrook Pike
         Knoxville, TN 37096

                                    L E A S E

         THIS LEASE, made and entered into this 7th day and effective as of
March, 2001, and effective as of October 1, 2000, by and between THE UNIVERSITY
OF TENNESSEE, hereinafter called the Lessor, and TRISTAR ENTERPRISES, INC.,
hereinafter called the Lessee.

                                   WITNESSETH:

         The parties hereto, for the considerations hereinafter mentioned,
covenant and agree as follows:

         1.       DESCRIPTION: The Lessor hereby leases unto I, Lessee those
premises with the appurtenances thereto situated in the State of Tennessee,
County of Shelby, City of Memphis, in the Van Vleet Building at 3 N. Dunlap
Street. The premises above are more particularly described as follows:

         Approximately 2,050 rentable square feet of Office Space located on the
second floor and identified on attached Addendum Number One as C202, C206, C207,
C208, C212, C216, C219, C223, C224, C226 and C228. Approximately 4,818 rentable
square feet of Laboratory Space located on the third floor and identified on
attached Addendum Number Two as N321, N324. N324A, N325, N326, N326A, N328,
N328A, N329, N330, N333, N333A, N334, N334A, N334B. Plans for the building are
located in the Office of facilities at The University of Tennessee Health
Science Center in Memphis, Tennessee and are incorporated by reference as if
fully set out herein.

Being part of the same property described in the last recorded instrument
conveyed to Lessor in Plat Book No. I, Page 69. recorded in the Register's
Office, Shelby County, Tennessee. (Reference Instrument No. 6005-287 -no other
recorded deeds were located).

         2.       TERM: The term of this lease shall commence on October 1,
2000, and shall end on September 30, 2005, with such rights of termination
and/or extension as may be hereinafter expressly set forth. Should the Lessee
occupy the premises beyond the term of this lease such occupancy shall in no
event be year-to-year but at the will of the Lessor.

         3.       RENT: The Lessee shall pay annual rent of $94,820 ($11.00 per
rentable square foot of Office Space and $15.00 per rentable square foot of
Laboratory space), payable in installments of $7,901.67 per month. The rental
cost may subsequently be adjusted each July 1 and shall be based on the
percentage difference between the two most recent annual State and Local Index
values listed in Table 3.8B Real Government consumption Expenditures by Type and
Real Gross Investment by Type (formerly entitled Government Purchases by Type in
Constant Dollars) contained in the applicable July issue of the Department of
Commerce's Survey of Current Business. For example, if this adjustment factor
had been put into effect prior to July 1, 1996, a 2.3% increase in the prior
rate would be permissible for the period of July 1, 1996 - June 30, 1997 (the
July 1996 issue of the Department of Commerce's Survey of Current Business lists
the 1995 State and Local Index value as 788.6 and the 1994 value as 770.5
(788.6/770.5 = 1.023)).

         4.       PURPOSE: The premises hereby leased shall only be used for
education, research, or public service activities. Lessee shall not permit or
suffer any act or event to occur upon the premises which is extra hazardous on
the account of tire or explosion.
<PAGE>

Tristar Enterprises, Inc.
Page 2 of 5

         Further Lessee covenants to comply with all City laws and ordinances
and State and federal laws in regard to nuisances, insofar as the premises are
concerned and to make no unlawful or offensive use of the premises.

         5.       ASSIGNMENT AND SUBLETTING: The Lessee shall neither assign
this Lease nor sublet the premises in whole or part without the written consent
of the Lessor. Further, the Lessee shall not permit the use or occupation of
said premises by anyone other than Lessee without the written consent of the
Lessor.

         6.       REPAIR/MAINTENANCE: The Lessee accepts the premises in its
present physical condition. During the lease term, the Lessor shall maintain the
leased premises and appurtenances which he provides in good repair and
tenantable condition, including, but not limited to, the maintenance and repair
of the elevators, plumbing, heating, electrical, air conditioning and
ventilating equipment and fixtures to the end that all such facilities are kept
in good operative condition except in case of damage arising solely from a
willful or negligent act of' the Lessee's agent, invitee, or employee.

         The Lessee shall take good care of the premises hereby leased and the
appurtenances thereof and neither commit nor permit any waste. At the end or
other expiration of the term of this Lease, the Lessor shall deliver up said
premises in as good order or condition as they were at the beginning of this
Lease, ordinary wear and tear thereof and damage by earthquake the elements,
acts of God, or fire over which the Lessee has no control excepted.

         7.       ALTERATIONS: The Lessee shall not make any alterations,
additions or improvements in the premises without first obtaining written
consent from the Lessor. All alterations, additions or improvements made by the
Lessee shall inure to the benefit of the property of the Lessor upon the
termination and end of this lease unless hereinafter specified to the contrary
or otherwise agreed to in writing and signed by both parties.

         8.       UTILITIES: The costs associated with utilities and janitorial
services will be included as part of the rent as set forth in paragraph 3.

         9.       INSPECTION: 'The Lessor shall have the right, upon notice to
the Lessee, to enter the leased premises at reasonable times in order to
inspect, render services or make necessary repairs to the premises.

         10.      FIRE AND CASUALTY: If the premises be destroyed by fire or
other casualty, this Lease shall immediately terminate. In the case of partial
destruction or damage so as to render the premises untenantable, either party
may terminate the Lease by giving written notice to the other within
fourteen(14) days thereafter.

         11.      LIABILITY: Lessor shall not be liable for any property or
valuables destroyed, damaged, lost, stolen, taken or missing from the Premises,
the Lessee agreeing to sufficiently protect, secure, insure, and safeguard any
and all property maintained or stored upon the Premises. Any property placed on
or within the Premises is maintained strictly at Lessee's own risk. The Lessor
agrees to provide fire and casualty insurance or self insurance in amounts
sufficient to protect its own interest in the Building only.

         Lessee, its successors and assigns, shall indemnify and hold harmless
Lessor and the State of Tennessee from any and all claims, costs or damages, and
judgments of whatsoever nature, including without limitation costs and expenses
incurred by Lessor or the State in the defense of any action, arising out of the
activities of Lessee on the premises pursuant to this Lease and to assume all
responsibility and liability therefore.

         The Lessee, its successors and approved assigns, agrees to maintain
adequate public liability insurance and will provide satisfactory evidence of
such insurance to the State. Further, the liability limits of this insurance
must not be less than the exposure and limits of' the State's liability under
the Claims Commission Statute, T.C.A. Section 9-8-307, as it may be from time to
time amended and/or construed by the claims commission and courts. This statute
currently limits liability of the State to $300,000 per claimant, $1,000,000 per
occurrence. The insurance policy shall include a provision for the insurance
company to notify the State in writing of any cancellation or changes of the
policy at least 30 days in advance of the cancellation or change.
<PAGE>

Tristar Enterprises, Inc.
Page 3 of 5

         12.      TERMINATION/EXTENSION: Notwithstanding any other provision to
the contrary in the event that the Lessee becomes insolvent or bankruptcy
proceedings are filed against or by the Lessee, his heirs or assigns in any
court whatsoever, it shall give the rights to Lessor or its assigns, at their
option, to immediately declare this contract null and void and at once resume
possession of the property. No receiver, trustee or other judicial officer shall
have any right, title or interest in or to the above described property by
virtue of' this contract.

         Further, if the Lessee shall fail or neglect to make any payment of
rent when due, vacate the premises without notice to the Lessor or shall violate
any of' the provisions of this Lease, the Lessor, without any other demand or
notice, may at Lessor's option, immediately terminate this Lease and if
necessary require the Lessee to vacate the leased premises.

         In lieu of any termination right mentioned herein or in conjunction
therewith, Lessor may pursue any other lawful right or remedy incident to the
relationship created by this Lease. Should the Lessor at any time seek to
rightfully recover possession of the premises and be obstructed or resisted
therein, and any litigation thereon ensue, the Lessee shall be bound to pay the
Lessor reasonable attorney's fees and all court costs.

         It is agreed that either party shall have the right and privilege to
terminate the agreement by giving a written notice to the other party at least
90 days prior to the specified termination date.

         This lease may be extended by both parties agreeing to the terms and
conditions of such extension in writing and signed by all parties subject to the
approval of the State Building Commission.

         13.      NOTICES: All notices herein provided to be given, or which may
be given, by either delivered in person or by certified mail as follows:

         TO THE LESSOR:                          TO THE LESSEE:

         OFFICE OF REAL ESTATE MANAGEMENT        TRISTAR ENTERPRISES, INC.
         THE UNIVERSITY OF TENNESSEE             3 N. DUNLAP STREET
         432 COMMUNICATIONS BUILDING             MEMPHIS, TN 38163
         KNOXVILLE, TN 37996-0342

         14.      SPECIAL PROVISIONS: Prior to the execution of this lease the
following special provisions, if any, were agreed upon:

         a.       This agreement constitutes the entire agreement concerning the
least of this property. Any previous written or oral agreements between the
Lessee and the previous owners of the property are entirely superseded.

         b.       Additional space in the amount of approximately 1, 014
rentable square feet on the first floor and 976 rentable square feet on the
third floor will be required at a later date. This lease will be amended at that
time to include this additional space at the then-current rental rate.

         c.       This Lease may not be amended, modified or in any way changed
except by written agreement signed by both parties.

         d.       This Lease is not binding upon the Lessor until the fully
executed document is delivered to the Lessee.

         15.      CERTIFICATION: The Lessee hereby certifies that Lessee is
neither now nor within the past six (6) months has been an official or employee
of 'The University of' Tennessee or any other agency or institution of the State
of Tennessee and that no official or employee of The University of-Tennessee or
no official or employee of the University or one of those agencies has any
personal interest in the leased premises.
<PAGE>

Tristar Enterprises, Inc.
Page 4 of 5

         IN WITNESS WHEREOF, this lease has been executed by the parties hereto
on the day and year first above written.

LESSOR                                          LESSEE

THE UNIVERSITY OF TENNESSEE                     TRISTAR ENTERPRISES, INC.

BY: /s/ illegible                               BY: /s/ illegible
    __________________________________             ____________________________
    VICE PRESIDENT                              ITS: President & CEO

STATE OF TENNESSEE

BY: /s/ C. Warren Neel,
   -----------------------------------
    C. WARREN NEEL, PhD, Commissioner
    Finance and Administration

APPROVED:

BY: /s/ Paul G. Summers
   -----------------------------------
    Paul G. Summers
    Attorney General

BY: /s/ Don Sundquist
   -----------------------------------
    Don Sundquist
    Governor
<PAGE>

Tristar Enterprises, Inc.
Page 5 of 5

                          AUTHENTICATION FORM FOR LEASE

                                     BETWEEN

                             THE STATE OF TENNESSEE

                                       AND

                            TRISTAR ENTERPRISES, INC.

STATE OF TENNESSEE
COUNTY OF KNOX

Personally appeared before me, the undersigned Notary Public for Knox County,
Emerson H. Fly, Vice-President of the University of Tennessee, with whom I am
personally acquainted (or proved to me on the basis of satisfactory evidence,
and who, upon oath, acknowledged that he/she is the Vice-President of the
University of Tennessee and that he/she as Vice-President, being authorized so
to do, executed the foregoing instrument for the purpose therein contained by
signing the name of the State by himself as Vice-President.

                  Witness my hand and seal at office, this 25th day of July,
2001.

                                           /s/ Sophie Diane Martin Hopkins
                                    --------------------------------------------
                                                    Notary Public

                                           My Commission Expires:

                                                        6-26-02

STATE OF TENNESSEE
COUNTY OF DAVIDSON

Personally appeared before me, the undersigned, Notary Public for Davidson
County, C. Warren Neel, PhD, with whom I am personally acquainted and who, upon
oath, acknowledged that he is the Commissioner of Finance and Administration and
that he as Commissioner, being authorized so to do, executed the foregoing
instrument for the purpose therein contained by signing the name of the State of
Tennessee, by himself as Commissioner.

                  Witness my hand and seal at office, this 27th day of August,
2001.

                                                        /s/ Margaret Tolleson
                                             -----------------------------------
                                                        Notary Public

                                           My Commission Expires:

                                                        Nov. 29, 2003

<PAGE>

                          AUTHENTICATION FORM FOR LEASE
                               MADE BY AND BETWEEN

                            TRISTAR ENTERPRISES, INC.

                           AND THE STATE OF TENNESSEE

                                 DATED_________

STATE OF TENNESSEE

COUNTY OF SHELBY

Before me ______________________________, a Notary Public in and for said County
and State aforesaid, personally appeared _______________________________, with
whom I am personally acquainted, and who, upon oath, acknowledged
himself/herself to be the ___________________________ of
___________________________, the within named Lessor, a corporation, and that
he/she as such __________________________, being authorized so to do, executed
the foregoing lease for the purposes therein contained, by signing the name of
the Corporation by himself/herself as __________________________________.

Witness my hand and seal, at the office in Memphis, TN, this 7th day of March,
2001.

                                                        Notary Public
                                                        ________________________

My Commission Expires:

         March 12, 2002<PAGE>

                                                                   EXHIBIT 10.14

                                    SUBLEASE

         This Sublease made and entered into as of this 1st day of October 2000
by and between TRISTAR ENTERPRISES, INC., a Tennessee nonprofit corporation
("Sublessor") and GENOTHERAPEUTICS, INC., a Tennessee corporation ("Sublessee").

                                 R E C I T A L S

         WHEREAS. the Sublessor and The University of Tennessee have entered
into a Lease dated October 1, 2000 (the "Primary Lease"), a copy of which is
attached hereto as Exhibit A.

         WHEREAS, the Sublessor desires to sublease a portion of the premises
leased by the original Primary Lease to the Sublessee.

         NOW THEREFORE, in consideration of the foregoing and other good and
valuable considerations set forth herein, the parties agree as follows:

         1.       The Sublessor hereby subleases unto the Sublessee those
premises with the appurtenances thereto appertaining situated in the State of
Tennessee, County of Shelby, City of Memphis, located at 3 North Dunlap Street,
more particularly described as follows:

                  Approximately 4.818 rentable square feet of
                  laboratory space located on the Third Floor of the
                  Van Vleet Building, 3 North Dunlap Street, Memphis,
                  Shelby County, Tennessee. Being part of the same
                  property described in the last recorded instrument
                  conveyed to The University of Tennessee in Plat Book
                  No. 1, Page 69, recorded in the Register's Office,
                  Shelby County, Tennessee. (Reference Instrument No.
                  6005-287). Plans for the building can be found in the
                  Office of Facilities at The University of Tennessee
                  Health Science Center, Memphis, Tennessee.

         2.       The Sublessee shall pay annual rent of $72,270.00 ($15.00 per
square foot), payable in installments of $6,022.50 per month. The rental cost
may be subsequently adjusted each July 1 and shall be based on the percentage
difference between the two most recent annual State and Local Index values
listed in Table 3.8B-Real Government Consumption Expenditures by Type and Real
Gross Investment by Type (formerly entitled Government Purchases by Type and
Constant Dollars)contained in the applicable July issue of the Department of
Commerce's Survey of Current Business. For example, if this adjustment factor
had been put into effect prior to July 1, 1996, a 2.3 percent increase in the
prior rate would be permissible for the period of July 1, 1996 through June 30,
1997 (the July 1996 issue of the Department of Commerce's Survey of Current
Business lists the 1995 State and Local Index value at 788.6 and the 1994 value
at 770.5 (788.6/770.5 equals 1.023)).

         3.       Except for Section 1 and Section 3 of the Primary Lease, the
Sublessee hereby agrees to be bound by the terms and the conditions of the
Primary Lease as if the Sublessee were the Lessee thereunder.

<PAGE>

         4.       The effectiveness of this Sublease is subject to the written
consent of The University of Tennessee approving this Sublease.

         5.       All notices required under this Sublease shall be sent to the
following addresses:

                  To the Sublessor:              To the Sublessee:

                  Tristar Enterprises, Inc.      Genotherapeutics, Inc.
                  3 North Dunlap Street          _______________________________
                  Memphis, Tennessee 38163       _______________________________

         IN WITNESS WHEREOF, this Sublease has been executed by the parties as
of the date hereinabove written:

                                                  TRISTAR ENTERPRISES, INC

                                                  By: /s/ illegible
                                                     _________________________

                                                  Title: President

                                                  GENOTHERAPEUTICS, INC.

                                                  By: /s/ Marc Hanover
                                                     ---------------------------

                                                  Title: President

<PAGE>

                            Tristar Enterprises, Inc.
                                     Phase I
                               Space Requirements

<TABLE>
<CAPTION>
Office #    Sq Ft   Tristar     UT     Office
<S>         <C>     <C>        <C>     <C>
206          325     162.5     162.5   Scott
216          242       121       121   Banton
232          239                 239   Palmer
230          140                 140   UTRC
224          343     171.5     171.5   CMO
228          161       161             IRB
202          107       107             IRB
208          176       176             ADMIN
221          141                 141   UT STORAGE
223          139       139             ACC'T/Contract Mgr
226          161       161             CLINICAL/Coordinator
205          182                 182   RESEARCH
219          143        85        58   Howell
212          176        88        88   Jennings
207          348       174       174   Conf. Rm

3rd Floor   3750      3750             Lab (sub-GTX)*
            ----      ----     -----

Total       6773      5296      1477
</TABLE>

*Room # 333, 333A, 329, 325, 321, 324, 324A, 326, 326A, 328, 328A, 334, 334A,
         334B, & 330 (cold room)

                              Phase II (Expansion)

First Floor: Room # 106, 106A, 106B, 106C, and 107 (approx. 700 sq ft)

Third Floor: Room # 319 & 320 (approx. 750 sq ft)

<PAGE>

                               SUBLEASE AMENDMENT

         This Amendment is to the sublease made between TRISTAR ENTERPRISES,
INC., a Tennessee nonprofit corporation (" Sublessor")and GENOTHERAPEUTICS,
INC., a Tennessee corporation ("Sublessee") signed on October 1, 2000.

         1.       The Sublessor hereby subleases unto the Sublessee those
premises with the appurtenances thereto situated in the State Of Tennessee,
County of Shelby, City of Memphis, located at 3 North Dunlap Street, more
particularly described as follows:

                  a.       Effective February 1,2001, approximately 7,374
         rentable square feet of office space located on the Third Floor of the
         Van Vleet Building, Rooms C300, C301, C302, C303, C304, C305, C310,
         C311, C312, C313, C314, C315, C315A, C316, C317, C319, C322, C322A,
         C322B, C322C, C323, C325, C326, C327, C327A, C329, C329A, C332, C333,
         C334, C335, S301, S302, S303, S305, S306,

                  b.       Effective June 1, 2001 approximately 966 rentable
         square feet of laboratory space located on the Third Floor of the Van
         Vleet Building, Rooms N319, N320, N320A, 3 North Dunlap Street,
         Memphis, Shelby County, Tennessee. Being part of the same property
         described in the last recorded instrument conveyed to The University of
         Tennessee in Plat Book No., 1, Page 69, recorded in the Register's
         Office, Shelby County, Tennessee. (Reference Instrument No. 6005-287)
         Plans for the building can be found in the Office of Facilities at The
         University of Tennessee Health Science Center, Memphis, Tennessee.

         2.       The Sublessee shall pay annual rent of $81,114.00 ($11.00 per
square foot) payable in installments of $6,759.50 per month for the office
space. The Sublessee shall pay annual rent of $14,490.00 ($15.00 per square
foot) payable in installments of $1,207.50 per month for the additional
laboratory space.

         3.       All other terms remain unchanged.

<PAGE>

         IN WITNESS WHEREOF, this Sublease amendment has been executed by the
parties as of the date hereinabove written:

                                                  TRISTAR ENTERPRISES, INC.

                                                  By: /s/ illegible
                                                     ___________________________

                                                  Title: President & CEO

                                                  GENOTHERAPEUTICS, INC.

                                                  By: Marc Hanover
                                                      --------------------------

                                                  Title: President

<PAGE>

                           SUBLEASE AMENDMENT NUMBER 2

         This Amendment Number 2 is to the sublease between Tristar Enterprises,
Inc., a Tennessee nonprofit corporation ("Sublessor") and GTx, Inc., a Tennessee
corporation ("Sublessee") signed on October 1, 2000.

         A copy of the sublease, signed on October 1, 2000 and a copy of the
original Sublease Amendment, which was effective on February 1, 2001, are
attached to this Sublease Amendment Number 2.

         1.       The Sublessor hereby subleases unto the Sublessee those
                  premises with the appurtenances thereto situated in the State
                  of Tennessee, County of Shelby, City of Memphis, located at 3
                  North Dunlap Street, more particularly described as follows:

                  Effective October 1, 2002, approximately 644 rentable square
                  feet of office space located on the First Floor of the Van
                  Vleet Building, Rooms C119, C120, C121, C122, C126.

         2.       The Sublessee shall pay annual rent of $7,087.73 ($11.00 per
                  square foot) payable in installments of $590.64 per month for
                  the office space.

         3.       All other terms remain unchanged.

         In witness whereof, this Sublease Amendment Number 2 has been executed
by the parties as indicated below:

TRISTAR ENTERPRISES, INC.                       GTx, INC.

By: /s/ Robert L. Palmer                        By: /s/ Mark E. Mosteller
   ---------------------------------               -----------------------------

Name: Robert L. Palmer                          Name: Mark E. Mosteller

Title: President & CEO                          Title: Chief Financial Officer

Date: 11/5/02                                   Date: 11/5/02

<PAGE>

Amendment Number 2

<TABLE>
<S>           <C>
C0119              115
C0120              121
C0121              105
C0122               85
C0126               60
              --------
                   486
              x 1.3258
              --------
                644.34
                  x 11
              --------
              7,087.73
                590.64
</TABLE>

<PAGE>

                           SUBLEASE AMENDMENT NUMBER 3

         This Amendment Number 3 is to the sublease between Tristar Enterprises,
Inc., a Tennessee nonprofit corporation ("Sublessor")and GTx, Inc., a Tennessee
corporation ("Sublessee") signed on October 1, 2000.

         A copy of the sublease, signed on October 1, 2000, a copy of the
original Sublease Amendment, and a copy of Sublease Amendment Number 2, are
attached to this Sublease Amendment Number 3.

         1.       The Sublessor hereby subleases unto the Sublessee those
                  premises with the appurtenances thereto situated in the State
                  of Tennessee, County of Shelby, City of Memphis, located at 3
                  North Dunlap Street, more particularly described as follows:

                  Effective January 1, 2002, approximately 2,437 rentable square
                  feet of office space located on the First Floor of the Van
                  Vleet Building, Rooms C106, C106A, C106B, C106C, C106D, C106E,
                  C106F, C106G, C106H, C107, C110, and C111.

         2.       The Sublessee shall pay annual rent of $120.00 payable in
                  installments of $10.00 per month for the space.

         3.       All other terms remain unchanged.

         In witness whereof, this Sublease Amendment Number 2 has been executed
by the parties as indicated below:

TRISTAR ENTERPRISES, INC.                   GTx, INC.

By: /s/ Robert L. Palmer                    By: /s/ Mark E. Mosteller
   ---------------------------------           ---------------------------------

Name: Robert L. Palmer                      Name: Mark E. Mosteller

Title: President & CEO                      Title: CFO

Date: 11/6/02                               Date: 11/5/02

<PAGE>

                                    GTx, INC.
                              DETAIL OF CLEAN ROOM
                              CONSTRUCTION EXPENSES
        CLEAN ROOM LOCATED ON THE FIRST FLOOR OF THE VAN VLEET BUILDING,
                             3 NORTH DUNLAP STREET

<TABLE>
<CAPTION>
     VENDOR                        ITEM                    INVOICE NUMBER     AMOUNT
---------------------------------------------------------------------------------------
<S>                   <C>                                  <C>              <C>          <C>
Clean Rooms West      Clean room construction and HVAC            18593     $10,303.94
Clean Rooms West      Clean room construction and HVAC            18594       1,251.00
Clean Rooms West      Clean room construction and HVAC            18510      73,657.55
Clean Rooms West      Clean room construction and HVAC            17377       9,329.05   $  94,541.54
                                                                            ----------

Steris                Autoclave-sterilizer                    101305900      53,648.99
Steris                Autoclave-sterilizer                    101451916       3,861.28
Steris                Autoclave-sterilizer                    101627455         506.37
Steris                Autoclave-sterilizer                    101625106       2,680.81
Steris                Autoclave-sterilizer                    101694378       3,289.97      63,987.42
                                                                            ----------

Quality Cryogenics    Special piping for liquid nitrogen           3552       1,500.00
Quality Cryogenics    Special piping for liquid nitrogen           6229       4,580.00
Quality Cryogenics    Special piping for liquid nitrogen           6228       8,603.00      14,683.00
                                                                            ----------

White Plumbing        Piping for gases                             3107       5,032.00       5,032.00
                                                                            ----------

Nexair                Gas manifolds                              542767         918.11
                                                                 553743         125.57
                                                                 553737       1,266.53
                                                                 534143       1,742.30
                                                                 534131       5,265.70
                                                                 502403       7,704.05
                                                                 594376          68.78      17,091.04
                                                                            ----------

Pure Water Solutions  Sterilizer Feed Water System                64381       3,072.14       3,072.14
                                                                            ----------   ------------
                      Total Clean Room Costs
                        Incurred by GTx, Inc.                                            $ 198,407.14
                                                                                         ============
</TABLE>

<PAGE>

                           SUBLEASE AMENDMENT NUMBER 4

         This Amendment Number 4 is to the sublease between Tristar Enterprises,
Inc., a Tennessee nonprofit corporation ("Sublessor")and GTx, Inc., a Tennessee
corporation ("Sublessee") signed on October 1, 200l.

         A copy of the sublease, signed on October 1, 2000, a copy of the
original Sublease Amendment, a copy of Sublease Amendment Number 2, and a copy
of Sublease Amendment Number 3 are attached to this Sublease Amendment Number 4.

         1.       The Sublessor hereby subleases unto the Sublessee those
                  premises with the appurtenances thereto situated in the State
                  of Tennessee, County of Shelby, City of Memphis, located at 3
                  North Dunlap Street, more particularly described as follows:

                  Effective September 1, 2003, approximately 3 10 rentable
                  square feet of office space located on the First Floor of the
                  Van Vleet Building, Rooms C127 and C129.

         2.       The Sublessee shall pay annual rent of $3,410.00 ($11 per
                  square foot) payable in installments of $258.80 per month for
                  the office space.

         3.       All other terms remain unchanged.

         In witness whereof, this Sublease Amendment Number 4 has been executed
by the parties as indicated below:

TRISTAR ENTERPRISES, INC.                      GTx, INC.

By: /s/ Robert L. Palmer                       By: /s/ Mark E. Mosteller
   ----------------------------------             ------------------------------

Name: Robert L. Palmer                         Name: Mark E. Mosteller

Title: President & CEO                         Title: Chief Financial Officer

Date: 8/11/03                                  Date: 8/11/03

<PAGE>

                           SUBLEASE AMENDMENT NUMBER 5

         This Amendment Number 5 is to the sublease between Tristar Enterprises,
Inc., a Tennessee nonprofit corporation ("Sublessor")and GTx, Inc., a Tennessee
corporation ("Sublessee")signed on October 1, 2000,

         1.       The Sublessor hereby subleases unto the Sublessee those
                  premises with the appurtenances thereto situated in the State
                  of Tennessee, County of Shelby, City of Memphis, located at 3
                  North Dunlap Street, more particularly described as follows:

                  Effective September 1, 2003, approximately 831 rentable square
                  feet of office space located on the Second Floor of the Van
                  Vleet Building, Rooms S201, S202, S203, S205, and S206.

         2.       The Sublessee shall pay annual rent of $9,141.00 ($11 per
                  square foot) payable in installments of $761.75 per month for
                  the office space.

         3.       All other terms remain unchanged.

         In witness whereof, this Sublease Amendment Number 5 has been executed
by the parties as indicated below:

TRISTAR ENTERPRISES, INC.                       GTx, INC.

By: /s/ Robert L. Palmer                        By: /s/ Mark E. Mosteller
   -------------------------------------           -----------------------------

Name: Robert L. Palmer                          Name: Mark E. Mosteller

Title: President & CEO                          Title: Chief Financial Officer

Date: 8/5/03                                    Date: 8/7/03

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00057-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00057-of-00352.parquet"}]]