This zebrafish model, engineered for heat-shock inducible miR-21 overexpression specifically within beta cells, has been used to study how miR-21 overexpression leads to beta cell dedifferentiation. It was generated through swapping out the original H2B-GFP sequence with a pre-miR-21 amplicon in the transgenesis vector used to make the Tg(hs:CS) transgenic line. By intercrossing with Tg(ins:Cre)s924 fish, this further allows induction of miR-21 specifically in beta cells.