1. Department of Chemistry and Biochemistry and Institute for Marine Sciences, University of California Santa Cruz, Santa Cruz, California 95064, Henry Ford Health System, Department of Internal Medicine, Division of Hematology and Oncology, Detroit, Michigan 48202, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115