We are grateful to Dr. Susan Bonner-Weir and Brooke Sullivan for kindly providing an aliquot of the Ngn3 antibody and advice and assistance with immunostaining protocols. I.A.V. is supported by an NIH F31DK098931 award. E.D. was supported by the Juvenile Diabetes Research Foundation postdoctoral fellowship 3APF-2014-220-A-N. A.K.K.T. was supported by the Juvenile Diabetes Research Foundation postdoctoral fellowship 3-2013-236 and is currently supported by the Institute of Molecular and Cell Biology, A*STAR, NHG-KTPH SIG/14033, the NUHS-CG Metabolic In-Vitro Core Seed Funding, and JCO Career Development Award 15302FG148, A*STAR. R.N.K. is supported by Harvard Stem Cell Institute Award SG-0078-12-00 and NIH grants P01 DK036836, R01 DK67536, R01 DK103215, and R01 DK055523.