Exhibit 10.15

                             FIRST AMENDMENT TO THE
                          STOCK OPTION AWARD AGREEMENT
                             DATED DECEMBER 31, 2006
                                 BY AND BETWEEN
              PROTALIX BIOTHERAPEUTICS, INC. AND JANE HSIAO, PH.D.

      THIS FIRST AMENDMENT ("Amendment"), made effective as of February 28,
2007, by Protalix BioTherapeutics, Inc., a Florida corporation (the
"Corporation") and Jane Hsiao, Ph.D. ("Grantee") to that certain Stock Option
Award Agreement, dated December 31, 2006, by and between the Corporation and
Grantee (the "Agreement").

                              W I T N E S S E T H:

      WHEREAS, the Corporation and Grantee entered into the Agreement whereby
the Corporation granted Grantee an option to purchase 387,542 shares of the
common stock of the Corporation, subject to a certain vesting schedule (the
"Vesting Schedule") set forth therein (the "Option"); and

      WHEREAS, the parties desire to amend the terms of the Option to revise the
Vesting Schedule.

      NOW, THEREFORE, effective as of the date hereinabove written, the parties
hereto hereby agree that the Agreement shall be amended as follows:

1.    Section 2(a) is hereby amended in its entirety to read as follows:

            "(a) Right to Exercise. The Option shall be exercisable during its
term in accordance with the following Vesting Schedule:

               Percentage of Stock       Vesting Date
               -------------------       ------------
               40%                       On the first anniversary of the date of
                                         this Agreement; and

               15%                       On each of the following dates: June
                                         30, 2008, December 31, 2008, June 30,
                                         2009 and September 30, 2009.

Notwithstanding the foregoing, such vesting schedule shall cease and all
unvested options shall remain unvested in the event Grantee ceases to express
the willingness to serve on the Board of Directors of the Company and no longer
serves on such Board and, if not on the Board of Directors of the Company,
ceases to provide and has not provided any services to the Company of the same
type that was provided while such Grantee was a member of the Board of Directors
("Continuous Service"). In no event shall the Company issue fractional Shares."

2.    In all other respects, the Agreement shall remain unchanged by this
      Amendment.


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      IN WITNESS WHEREOF, the parties have caused this Amendment to be executed
the day and year first above written.

                                  PROTALIX BIOTHERAPEUTICS, INC.

                                  By:     /s/ David Aviezer
                                     -------------------------
                                  Name: David Aviezer, Ph.D.
                                  Title:   President and Chief Executive Officer

                                  GRANTEE

                                  /s/ Jane Hsiao
                                  ----------------------------------------------
                                  Jane Hsiao, Ph.D.

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