1. From the Department of Molecular Biology and Pharmacology (W.G., H.L., F.A., J.M.N.), Washington University School of Medicine, St. Louis, Mo; the Department of Neurosurgery (D.C.J.), Johns Hopkins University School of Medicine, Baltimore, Md; the Neuroscience Division (K.J.R.), Wyeth-Ayerst Research, Princeton, NJ; and the Department of Biochemistry and Cell Biology (J.S.T.), State University of New York, Stony Brook, NY.