1. Section on Islet Transplantation and Cell Biology (E.S.O., G.C.W.), Research Division, Joslin Diabetes Center and the Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215;
2. David H. Koch Institute of Integrative Cancer Research (A.V., D.G.A.), Department of Chemical Engineering, Division of Health Science and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139