1. Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
2. Department of Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany.
3. Department of Genetics, Harvard Medical School, and Division of Genetics, Brigham and Women’s Hospital, Boston, MA 02115, USA.
4. Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA.
5. Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland.
6. Departments of Pharmacological Sciences and Chemistry, Stony Brook University, Stony Brook, NY 11794, USA.