LEP and obesity due to melanocortin 4 receptor deficiency: Although Ksr2 is expressed in areas of the hypothalamus known to be involved in mediating leptin’s effects on food intake, such as the arcuate nucleus (Figure S4), previous studies performed in Ksr2−/− mice did not convincingly link leptin and melanocortin pathways to the obesity phenotype (Revelli et al., 2011).