FOXO1 and type 2 diabetes mellitus: A new look at phenotypic change was taken by the Accili group, which obtained data from mice lacking FoxO1 and suggested the novel hypothesis that in T2D β cells are dedifferentiated to a state of immaturity whereby they express neurogenin3, Oct4, Nanog, and L-Myc and no longer make insulin.100 Some of these cells even adopted an α cell fate.