The undersigned, Biotechnology Value Fund, L.P., a Delaware limited partnership, Biotechnology Value Fund II, L.P., a Delaware limited partnership, BVF Investments, L.L.C., a Delaware limited liability company, BVF Partners L.P., a Delaware limited partnership, and BVF Inc., a Delaware corporation, hereby agree and acknowledge that the information required by Schedule 13D, to which this Agreement is attached as an exhibit, is filed on behalf of each of them. The undersigned further agree that any amendments or supplements thereto shall also be filed on behalf of each of them.

Dated: September 27, 2002

	BIOTECHNOLOGY VALUE FUND, L.P.

	By:	BVF Partners L.P., its general partner

		By:	BVF Inc., its general partner

			By:	/s/ MARK N. LAMPERT Mark N. Lampert President

	BIOTECHNOLOGY VALUE FUND II, L.P.

	By:	BVF Partners L.P., its general partner

		By:	BVF Inc., its general partner

			By:	/s/ MARK N. LAMPERT Mark N. Lampert President

	BVF INVESTMENTS, L.L.C.

	By:	BVF Partners L.P., its manager

		By:	BVF Inc., its general partner

			By:	/s/ MARK N. LAMPERT Mark N. Lampert President

	BVF PARTNERS L.P.

	By:	BVF Inc., its general partner

		By:	/s/ MARK N. LAMPERT Mark N. Lampert President

	BVF INC.

	By:	/s/ MARK N. LAMPERT Mark N. Lampert President