1. INSERM U473, 84 rue du Général Leclerc, 94276 Le Kremlin-Bicêtre Cedex, France, Département de Biochimie, Université de Genève, CH-1211, Genève 4, Switzerland, Department of Medical Chemistry, School of Pharmacy, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298-0540, and Institut de Pharmacologie et Biologie structurale, CNRS 205 Route de Narbonne 31077 Toulouse, France