1. From the Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY (C.N.Y., S.D.B., R.L.D.); Internal Medicine, University of Iowa, Iowa City, IA (D.A.M., A.L.M.); and Cell and Developmental Biology, Weill Cornell Medical College, New York, NY (A.L.M., R.L.D.).