Since the levels of MAFA and MAFB are more sensitive to metabolic stressors in relation of other islet-enriched TFs (34), we propose that compromised MAF expression upon exposure to obesity- and insulin resistance–induced effectors leads to β cell dysfunction and reduced cell identity due to induction of GAST+ cell–associated gene products. This evidence concerns the gene GAST and obesity due to melanocortin 4 receptor deficiency.