1. From the Departments of Molecular Biology and Pharmacology (C.M., S.B., J.M.N.), Cell Biology and Physiology (T.P.F.), and Radiology (T.K.P.), Washington University Medical School, St Louis, Mo; and INSERM U533, L’Institut du Thorax and Université de Nantes (S.D.), Faculté de Médecine, France. Present address for S.B.: Department of Pharmacology, University of Washington, Seattle.