SENP1 and diabetes mellitus: However, the structures of pancreatic islets in SENP1-AdipoqKO, SENP1-PdgfRKO and SENP1-aP2KO mice were drastically disrupted with increased TdT-mediated dUTP nick end labelling (TUNEL)-positive apoptosis of β cells after onset of diabetes and more severe at late stages (Fig. 3a–c for SENP1-aP2KO; Supplementary Fig. 2 for SENP1-AdipoqKO and SENP1-PdgfRKO).