1. Department of Chemistry, University of Basel, 4056 Basel, Switzerland
2. Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, United States
3. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, United States
4. Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
5. Department of Biological Chemistry, University of California, Irvine, California 92697, United States