1 Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA. Electronic address: gordon.weir@joslin.harvard.
2 Section on Immunobiology, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA.
3 Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA.