1.Present address: Novartis Institutes for BioMedical Research, Diabetes and Metabolism Disease Area, Cambridge, MA 02139, USA
2Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
3Present address: Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94143-0448, USA.
4The Whitehead Institute, Cambridge, MA 02142, USA
5Diabetes and Metabolism Disease Area, Novartis Institutes for BioMedical Research, Inc., Cambridge, MA 02139, USA
6Institute of Cancer Genetics and Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
