PARP1 and diabetes mellitus: In Section 6, we described that PARP inhibitors induced the regeneration of pancreatic β-cells in 90% depancreatized rats, thereby ameliorating the surgical diabetes.154,156) Then, we isolated Reg (Regeneratinggene) from the regenerating islet-derived cDNA library157,160) and established the Reg-Reg receptor system for the cell regeneration/proliferation (Figs. 16 and 17).