RASGRP1 and type 1 diabetes mellitus: To further study the role of DLK1 and RASGRP1 in regulating β cell apoptosis in T1D condition, we also examined the early apoptotic rate of DLK1−/− and RASGRP1−/− β-like cells treated with cytokine cocktail (TNFα, IL1β and IFNγ).