CUSIP NO. 75886F 10 7 13G PAGE 16 -------- of ------- 16 PAGES ---

CUSIP NO. 75886F 10 7               13G     PAGE 16 -------- of ------- 16 PAGES
                                    ---


                                                                       Exhibit 5
                                                                       ---------

               Joint Filing Agreement Pursuant to Rule 13d-1(k)(1)

The undersigned hereby agree that this document shall be filed on behalf of each
of  them.


                                                 FELDON  INVEST  SA


                                             By:  /s/  Xxxxxx X. Xxxxx
                                                ------------------------------
                                                 Name:  Xxxxxx  X.  Xxxxx
                                                 Title:  Attorney-in-Fact


                                                 EMFELD  LTD


                                             By:  /s/  Xxxxxx X. Xxxxx
                                                ------------------------------
                                                 Name:  Xxxxxx  X.  Xxxxx
                                                 Title:  Attorney-in-Fact


                                                 BERTARELLI  &  CIE


                                             By: /s/  Xxxxxx X. Xxxxx
                                                 -----------------------------
                                                 Name:  Xxxxxx  X.  Xxxxx
                                                 Title:  Attorney-in-Fact


                                             By:  /s/  Xxxxxxx Xxxxxxxxxx*
                                                ------------------------------
    *By:  /s/  Xxxxxx X. Xxxxx                   Xxxxxxx  Xxxxxxxxxx
        -----------------------------
         Xxxxxx X. Xxxxx, Attorney-in-Fact



Dated:  March 30, 2001