from SC 13G
1 page
<page> Exhibit 1 Agreement Regarding Joint Filing 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 the Amendment to Schedule 13g, 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: May 11, 2001 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
