1. From the Departments of Biological Chemistry (G.G.H., J.E.V.E.), Medicine (M.H.S., V.L.H., T.E.Y., D.A.K., J.E.V.E., G.F.T.), Cell Biology (C.A.C., C.E.M.), and Biomedical Engineering (D.A.K., J.E.V.E.), Johns Hopkins University School of Medicine, Baltimore, Md; and Department of Medicine (F.G.A.), Mount Sinai School of Medicine, New York. Present address for G.G.H.: Cambridge Institute for Medical Research, University of Cambridge, United Kingdom. Present address for M.H.S.: Washington Hospital...