FOXM1 and diabetes mellitus: In mice, where two genes code for (pro)insulin (Ins1 and Ins2), Ins2 is predominantly transcribed in rare subsets of mTECs while Ins1 is dominantly expressed in murine islet β cells, which leads to a higher immunological tolerance to Ins2. This difference in the topography of Ins2 and Ins1 expression explains why breeding of Ins2−/− mice onto the NOD background markedly accelerates insulitis and diabetes onset (Thebault-Baumont et al., 2003), while the incidence of insulitis and autoimmune diabetes is considerably reduced in Ins1−/− congenic NOD mice (Moriyama et al., 2003).