Nkx2.2 is essential for the generation of insulin producing cells in mice (Sussel et al. 1998). In vivo binding of NKX2.2 to the endogenous insulin gene was shown by ChIP analysis in murine beta-cell lines (Cissell et al. 2003).

Insulin was markedly reduced in one Pax6 mutant model (Sander et al. 1997), but not in another (St-Onge et al. 1997). Pax6 has been shown to bind the insulin gene in chromatin immunoprecipitation studies (Cissell et al. 2003).

Binding of Pdx1 to the 5'-flanking region of the Insulin gene was observed in vitro (Ohlsson et al. 1993) and in transient transfection studies with rat cell lines (Serup et al. 1996). Reduced activity of Ins1 was reported in mature murine beta cells with targeted disruption of Pdx1 (Ahlgren et al. 1998; Holland et al. 2002). This is consistent with the expression profile from the dominant negative suppression of Pdx1 in rat insulinoma INS1 cell line-derived stable clones (Wang et al. 2001). ChIP experiments confirmed that Pdx1 binds in vivo to the Insulin gene in murine beta cell lines (Chakrabarti et al. 2002).