1. Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, Department of Chemistry, Columbia University, New York, New York 10027, Department of Biochemistry and Molecular Biology, University of Debrecen, Debrecen, Hungary, Institute of Nutritional Science, University of Potsdam, Potsdam, Germany, and Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021