It has been reported previously that mice overexpressing Cyp7a1 is protected against high fat diet-induced hypercholesterolemia, obesity and insulin resistance.18, 19 It has been found that peroxisome proliferator-activated receptor α coactivator-1α (PGC-1α) is activated by p38α MAPK20 and that PGC-1α activates CYP7A1 expression in activation of the CYP7A1 promoter.21 Thus, p38α MAPK might activate CYP7A1 expression in activation of the CYP7A1 promoter in part through PGC-1α. The gene discussed is CYP7A1; the disease is obesity due to melanocortin 4 receptor deficiency.