1. From the Department of Cell and Developmental Biology (X.C., J.R.P., M.R.G., R.L.D.) and Division of Neurobiology, Department of Neurology and Neuroscience (G.W., J.A., C.I.), Weill Cornell Medical College, New York, NY; Biomedical Sciences (C.N.Y., M.A.B., R.L.D.), College of Veterinary Medicine, Cornell University, Ithaca, NY.