1. From the Skirball Institute of Biomolecular Medicine (S.S., O.A., D.H.T.) and the Departments of Pediatrics (S.S., M.A.), Radiology (D.H.T.), and Pathology (D.H.T.), New York University Medical Center, New York, NY; the Joseph Stokes Research Institute (H.S.B.), Children’s Hospital of Philadelphia, Pa; and Roche Research Center (L.K., M.L.), Hoffmann-LaRoche Inc, Nutley, NJ.