1. Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4935, Department of Pharmacology and Biological Chemistry, Mt. Sinai School of Medicine of New York University, New York, New York 10029, Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, and Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4906