1. Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, United States
2. Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, United States
3. Stony Brook University, Molecular and Cellular Biology Program, Stony Brook, New York 11794, United States
4. University of the Sciences, 600 South 43rd Street, Philadelphia, Pennsylvania 19104, United States
5. Center for Biomolecular Structure and Organization, Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
6. Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, United States