Consistent with the “whitening” of BAT in obesity [49–52], we observed adipocytes with a “white-like” appearance, characterized by large lipid droplets, in the BAT sections from both high-fat diet-fed wild-type mice and mice deficient in either STK25 or MST3 (Fig. 4A). The gene discussed is STK24; the disease is obesity due to melanocortin 4 receptor deficiency.