Importantly, NF90–NF45 would function as a positive regulator in the expansion of the islets under the diabetic condition because the knockout of NF90–NF45 suppresses the islets expansion under the obesity-inducing metabolic stress (Fig. 3F–H, compared compare lanes control (HFD) and βNF45−/− (HFD)). This evidence concerns the gene ILF3 and obesity due to melanocortin 4 receptor deficiency.