1. INSERM U 386; Université Victor Segalen Bordeaux 2, 146 rue Léo-Saignat, F-33076 Bordeaux Cedex, France, Laboratory for Medicinal Chemistry, Rega Institute for Medical Research, Minderbroedersstraat 10, B-3000 Leuven, Belgium, Medical Research Council, Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom, and Institut Européen de Chimie et Biologie, 2 rue Robert Escarpit, F-33607 Pessac, France