Exhibit 4.3
FORM OF LOCK-UP AGREEMENT
April 22, 2005
Geron Corporation
230 Constitution Drive
Menlo Park, California 94025
Attention: Chief Financial Officer
Ladies and Gentlemen:
Geron Corporation, a Delaware corporation, (the "Company"), and
certain
investors including the undersigned, have
entered into a Common Stock Purchase
Agreement dated as of the date hereof (the
"Purchase Agreement"), providing for
the purchase of __________ shares (the
"Shares") of the Company's Common Stock,
par value $0.001 ("Company Common Stock")
and a warrant (the "Warrant") to
purchase __________ shares of Company
Common Stock (the "Warrant Shares") by the
undersigned. The Shares, the Warrant and
the Warrant Shares are collectively
referred to herein as the "Securities."
Pursuant to the Purchase Agreement, the undersigned hereby agrees
that,
without the prior written consent of the
Company, it will not, during the period
commencing on the date hereof and ending on
Apr
