1. Department
of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
2. Department
of Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, California 94305, United States
3. Department
of Chemistry, University of California, Berkeley, California 94720, United States
4. Department
of Chemistry, Stanford University, Stanford, California 94305, United States
5. Department
of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, United States
6. Howard Hughes Medical Institute, Chevy Chase, Maryland, United States