NKX6-1 and diabetes mellitus: The function of MAP3K15 has not been studied in any detail but it is highly homologous to Apoptosis-Signal-regulated Kinase 1 (ASK1), a gene that stimulates apoptosis in response to ER stress and other noxious stimuli [36], suggesting that an increased rate of apoptotic β cell loss may also be involved in the development of diabetes in patients carrying the NKX6–1 variants.