1. School of Clinical Sciences, University of Bristol, Bristol, U.K.
2. Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
3. Diabetes Research Institute, San Raffaele Scientific Institute, Milan, Italy
4. Institute of Diabetes Research, Helmholtz Zentrum München, and Forschergruppe Diabetes, Klinikum rechts der Isar, Technische Universität München, Neuherberg, Germany