1. Biological Chemistry Department, David Geffen School of Medicine, UCLA, Los Angeles, California 90095, United States
2. Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, United States
3. Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, United States
4. Department of Pathology, University of Michigan, Ann Arbor, Michigan 48109, United States