1. Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
2. Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
3. Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA.
4. Boston Biochem Inc., Cambridge, MA 02139, USA.
5. Department of Genetics and Howard Hughes Medical Institute, Division of Genetics, Brigham and Women’s Hospital, Harvard University Medical School, Boston, MA 02115, USA.
6. Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
7. Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.