1. INSERM U33 (S.L.B., E.-E.B.), France
2. URA 1218 Centre Nationale de la Recherche Scientifique (V.M., J.-M.R.) Pharmacologie Cellulaire 92296 Chatenay-Malabry Cédex, France
3. IFR 21 (C.M.-B.) 94276 Le Kremlin-Bicêtre Cedex, France
4. Department of Biochemistry (S.M.) Faculty of Medicine University of Montreal Montréal, Québec, H3TIJ4, Canada
5. Departments of Physiology and Medicine (J.H.W.) McGill University Montréal, Quebec, H361Y6 Canada