[1] Harvard Univ, Sch Med, Beth Israel Deaconess Med Ctr, Div Signal Transduct, Boston, MA 02115 USA
[2] Harvard Univ, Sch Med, Dept Cell Biol, Boston, MA 02115 USA
[3] Massachusetts Gen Hosp, Div Endocrinol, Boston, MA 02114 USA
[4] Boston Biomed Res Inst, Watertown, MA 02472 USA