1 Institute for Beta Cell Biology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research, and German Center for Diabetes Research (DZD e.V.), Düsseldorf, Germany.
2 Institute for Beta Cell Biology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research, and German Center for Diabetes Research (DZD e.V.), Düsseldorf, Germany Institute for Metabolic Physiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany lammert@hhu.de.