PPARD and obesity due to melanocortin 4 receptor deficiency: This includes increasing serum high-density lipoprotein,8 catabolism of fatty acids in skeletal muscle,3 regulation of serum glucose concentration,9 and terminal differentiation of a variety of cell types.10 Because of these important physiological roles, there remains strong interest in targeting PPARβ/δ for the treatment and prevention of diseases including atherosclerosis, diabetes, and obesity (reviewed in refs 11,12).