INS and diabetes mellitus: In an effort to find novel ways to recover functional beta cell mass in diabetes, based on a transgenic zebrafish model, Tg(ins:Flag-NTR), in which nitroreductase (NTR) is expressed under ins promoter and turns chemical MTZ into toxic products to induce apoptosis of beta cells, we previously performed in vivo chemical screens and identified hits that promoted beta cell proliferation [31, 32] and differentiation [33, 34].