EXHBIT 10.1



                           FIFTH AMENDMENT TO LEASE

      THIS FIFTH AMENDMENT TO LEASE ("Fifth Amendment") is made this 19th day of
March, 2008 (the "Effective Date"),  between DAVID D. BOHANNON  ORGANIZATION,  a
California corporation, herein referred to as "Landlord", and GERON CORPORATION,
a Delaware corporation, herein referred to as "Tenant".


                                   WITNESSETH:

      WHEREAS,  Landlord and Tenant entered into a Lease entitled "Business Park
Lease" dated January 20, 1993, for certain demised  premises  located at 194-200
Constitution Drive, Menlo Park,  California,  as more particularly  described in
said Lease, and

      WHEREAS,  the Lease has been  amended by a First  Amendment to Lease dated
July 26,  1993,  a Second  Amendment  to Lease dated  February 22, 1994, a Third
Amendment to Lease dated March 25, 1996,  and a Fourth  Amendment to Lease dated
March 23, 2004 (the "Fourth Amendment") (the Lease, as previously amended by the
foregoing amendments, is herein referred to as the "Lease"), and

      WHEREAS,  the Lease is scheduled to expire on July 31, 2008,  and Landlord
and Tenant desire to make certain amendments to the Lease and extend the demised
term of the Lease, all as more particularly set out hereinbelow.

      NOW, THEREFORE, in consideration of the covenants and conditions contained
herein, Landlord and Tenant agree to amend the Lease as follows:

      1.  The  demised  term of the  Lease is  hereby  extended  four (4)  years
commencing August 1, 2008, and the demised term shall expire on July 31, 2012 at
11:59 p.m.

      2. Effective as of the Effective Date, Section 1.3. of the Lease (Tenant's
option to extend the demised  term of the Lease),  which was  inserted  into the
Lease in  paragraph 2 of the Fourth  Amendment,  and Section  2.8. of the Lease,
which was inserted into the Lease in paragraph 4 of the Fourth Amendment,  shall
be deemed void and of no further force or effect,  as the parties have agreed to
extend the demised term of the Lease  pursuant to the  provisions  of this Fifth
Amendment.

      3. Base rent payable pursuant to Sections 2.1. and 2.2. of the Lease shall
be payable  during the extended  term as follows:  for the period from August 1,
2008,  to and  including  July 31,  2012,  base rent shall be the amount of Four
Hundred   Seventeen   Thousand  Two  Hundred   Eighty  Two  and  48/100  Dollars
($417,282.48)  per annum,  payable in twelve (12) equal monthly  installments of
Thirty  Four   Thousand   Seven  Hundred   Seventy  Three  and  54/100   Dollars
($34,773.54).

      4. In addition to the base rent set forth in Section 2.1 of the Lease,  as
revised  hereinabove,  Tenant shall continue to pay all items of additional rent
pursuant to the terms of the Lease.

      5. Tenant hereby  receives a new option to further extend the demised term
of the Lease;  therefore,  the  following  new Section 1.3. is inserted into the
Lease as of the Effective Date:


                                      -1-



            "Section  1.3.  Provided  that Tenant is not,  at the time  Landlord
      receives Tenant's written notice to exercise the following option, and has
      not been, in default  under any of the terms and  conditions of the Lease,
      which  default has not been cured within the  applicable  cure periods set
      forth in Article 13 of the Lease,  Tenant  shall have the option to extend
      the demised  term of the Lease for one (1)  additional  period of four (4)
      years upon the following terms and conditions:

            A. Tenant shall  exercise  the option by written  notice to Landlord
      given no later than one hundred  eighty  (180) days,  nor earlier than two
      hundred seventy (270) days, prior to the expiration of the demised term;

            B. The option term will commence on August 1, 2012, and shall extend
      for a period of four (4) years, up to and including July 31, 2016;

            C. There  shall be no further  options to extend,  there shall be no
      Landlord  inducement,  and  Landlord  shall not be required to perform any
      improvements  in the demised  premises or the building  prior to or during
      the option term;

            D. The option to extend may only be exercised by Geron  Corporation,
      provided that Geron  Corporation  may exercise the option on behalf of its
      sublessee if Geron  Corporation  has  subleased  any or all of the demised
      premises and Landlord has consented to such sublease. The option cannot be
      transferred  nor  can  it be  exercised  by  Geron  Corporation  if  Geron
      Corporation has assigned its rights under this Lease to a third party.

            E. The then current  payments for additional  rent shall continue to
      be adjusted  during the option  term  pursuant  to the  provisions  of the
      Lease;

            F. The base rent for each year of the option term shall  (subject to
      the  provisions  hereof) equal the Fair Market  Rental Value  (hereinafter
      defined). "Fair Market Rental Value" shall mean the market rent, including
      annual  increases  (if any),  being charged on the first day of the option
      term for similar space in buildings of comparable  quality as the building
      in which the demised  premises  is  situated  which are located in similar
      areas of the Cities of Menlo Park and Palo Alto. In  determining  the Fair
      Market Rental Value comparable transactions shall be considered, including
      without limitation,  length of lease term, landlord and tenant inducements
      and rent increases, if and to the extent then a part of market conditions.
      The rent on  comparable  leases  shall be adjusted to reflect the value or
      cost of such inducements  since neither Landlord nor Tenant shall have any
      obligation  to pay or  perform  any  such  inducements  (except  for  rent
      increases if applicable). For purposes of the determination of Fair Market
      Rental  Value it shall be assumed the  Landlord and Tenant are each ready,
      willing and able to enter into such a lease but are under no compulsion to
      do so.


                                      -2-



            Within twenty (20) calendar days after  Tenant's  written  notice of
      exercise,  Tenant shall advise Landlord of its estimate of the Fair Market
      Rental  Value for the  demised  premises.  Landlord,  within  twenty  (20)
      calendar days  thereafter,  shall advise Tenant in writing of its estimate
      of the Fair Market Rental Value. During the next twenty (20) calendar days
      the parties  shall meet and confer for the  purpose of agreeing  upon Fair
      Market  Rental  Value.  If the parties are then unable to agree,  then the
      Fair Market Rental Value shall be determined by an appraisal as herein set
      forth and the Fair Market Rental Value as so  determined  shall be binding
      upon  Landlord  and Tenant.  Within  ninety (90)  calendar  days after the
      Tenant's  notice of  exercise,  Landlord  and Tenant shall each appoint an
      appraiser and notify the other party in writing of its choice.  Thereupon,
      the two appraisers so elected shall elect a third appraiser  within thirty
      (30) calendar days of their appointment, unless during such period the two
      appraisers  shall have  agreed upon a Fair Market  Rental  Value,  or have
      reconciled  their  appraisals to within ten percent (10%) of each other in
      which  event the  average of the two  appraisals  will be the Fair  Market
      Rental  Value,  in which  case  their  determination  shall  be final  and
      binding.  If the two  appraisers  shall be  unable  to agree  upon a third
      appraiser,  then the  Landlord and Tenant  shall  immediately  request the
      Presiding  Judge of the San  Mateo  County  Superior  Court  to make  such
      selection.  The three appraisers shall meet and confer for a period not to
      exceed  sixty (60)  calendar  days and the  determination  of Fair  Market
      Rental Value by a majority of the three shall be final and binding. In the
      event that a majority  cannot agree,  then the third  (neutral)  appraiser
      shall direct each of the party appraisers to review their appraisals for a
      period of seven (7)  calendar  days and  return to a meeting  of the three
      appraisers  within five (5) calendar days  thereafter with each respective
      party  appraiser  having  indicated  their final  appraisal of Fair Market
      Rental Value in a sealed envelope and signed by that appraiser.  The third
      appraiser  will do the same.  The envelopes will be opened in the presence
      of the three  appraisers  and the Fair  Market  Rental  Value of the party
      appraiser  which is closest to the Fair Market  Rental  Value of the third
      appraiser  will be the final Fair Market  Rental  Value and binding on the
      parties.  Each party shall bear the cost of the  appraiser  selected by it
      and the cost of the third appraiser shall be shared equally (including all
      costs  associated  with an appointment by the Superior Court of San Mateo,
      if  applicable,  regardless of which party filed the  application).  To be
      appointed  as  an  appraiser  the  person  so  appointed  shall  hold  the
      professional  designation of MAI awarded by the American Institute of Real
      Estate  Appraisers  or such  designation  as may  then  be the  preeminent
      professional designation,  hold any licenses which may then be required by
      law,  and  have at least  five (5)  years  current  experience  appraising
      commercial/light  industrial  properties  in San Mateo  County.  The third
      (neutral)  appraiser  shall not have had any personal,  social or business
      relationship  with  either  party  or  any  of its  personnel  during  the
      preceding five (5) years.

            Notwithstanding the foregoing to the contrary, in no event shall the
      base rent for each year of the option term be reduced  below the base rent
      payable by Tenant for the last year (or partial year) of the demised term.

            When the base rent for the option term is determined pursuant to the
      above  provisions,  the parties shall promptly execute an amendment to the
      Lease  stating  the base rent to be paid  during the option  term.  In the
      event  Tenant  has  retained  the  services  of a real  estate  broker  to
      represent  Tenant  during  the  negotiations  of the  option  term,  it is
      expressly  understood  that  Landlord  shall  have no  obligation  for the
      payment of all or any part of a real estate  commission or other brokerage
      fee to Tenant's real estate broker in connection  therewith.  Tenant shall
      be solely  responsible  for the payments of fees for services  rendered to
      Tenant by such broker in connection with the option term.

            G. All other terms and conditions of the option term shall be as set
      forth in the Lease, and upon exercise by Tenant of the option as set forth
      herein all  references  to the  demised  term set forth in the Lease shall
      include the extended term."

      6. It is understood  and agreed that all other terms and conditions of the
Lease shall be and remain the same. Capitalized terms herein shall have the same
meaning as in the Lease. If there is any conflict between the provisions of this
Fifth  Amendment and the provisions of the Lease,  the  provisions  contained in
this Fifth Amendment shall control.


                                      -3-



      7. This Fifth  Amendment shall be construed under the laws of the State of
California. If any provision of this Fifth Amendment, or portion thereof, or the
application  thereof to any person or  circumstances  shall,  to any extent,  be
invalid or  unenforceable,  the remainder of this Fifth  Amendment  shall not be
affected  thereby and each provision of this Fifth  Amendment shall be valid and
enforceable to the fullest extent permitted by law.

      IN WITNESS  WHEREOF,  the parties have executed this Fifth Amendment as of
the date first hereinabove written.

TENANT:                                LANDLORD:
GERON CORPORATION,                     DAVID D. BOHANNON ORGANIZATION,
a Delaware corporation                 a California corporation


By   /s/ David L. Greenwood            By   /s/ Scott Bohannon
   -------------------------------       ------------------------------------
   David L. Greenwood                      Senior Vice President
   Executive Vice President and CFO

                                       By   /s/ Ernest Lotti Jr.
                                         ------------------------------------
                                            Secretary


                                      -4-