While female islets from S961-treated mice were not characterized here, the purified β cell population from male and female ob/ob mice — which represents a genetic model of obesity-induced glucose intolerance that manifests hyperglycemia, elevated plasma insulin (27), and loss of β cell MafA (28), akin to S961 treatment — were analyzed. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.