1. Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-4318, Institute of Biochemistry, Swiss Federal Institute of Technology, ETH Center, Universitätstrasse 16, CH-8092 Zurich, Switzerland, Department of Pharmacological Sciences, State University of New York at Stony Brook, Stony Brook, New York 11794, Department of Internal Medicine, University Hospital, CH-8091 Zurich, Switzerland, and Syndeco, St. Johann-Ring 19, CH-4056, Basel,...