EXHIBIT 1 Joint Filing Agreement We, the signatories of the statement to which this Joint Filing Agreement is attached, hereby agree that such statement is filed, and any amendments thereto filed by either or both of us will be filed, on behalf of...

                                    EXHIBIT 1

                             Joint Filing Agreement


     We, the  signatories of the statement to which this Joint Filing  Agreement
is attached,  hereby  agree that such  statement  is filed,  and any  amendments
thereto filed by either or both of us will be filed, on behalf of each of us.

         Dated:  July 12, 1999.

                          VULCAN VENTURES INCORPORATED



                         By:
                              --------------------------------
                              Xxxxxxx X. Xxxxx, Vice President


                               -------------------------------
                               Xxxx X. Xxxxx

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