Affiliation: | aDepartment of Stem Cell and Regenerative Biology, Howard Hughes Medical Institute, Harvard Stem Cell Institute, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138; and ;bDepartment of Pathology and Cell Biology, and ;cDivision of Molecular Genetics and Naomi Barrie Diabetes Center, College of Physicians and Surgeons, Columbia University, New York, NY 10032 |