MC4R and melanoma: Although previous studies have shown that activation of central MC3R and MC4R reduces PPAR-γ gene expression in hepatocytes [46] and Agouti, an endogenous MC1R antagonist, increases PPAR-γ levels in adipocytes [47], a very recent study has demonstrated that α-MSH induces both PPAR-γ upregulation and activation in B16-F10 melanoma cells [48].