To evaluate Erk5 involvement in response to metabolic stress from obesity and diabetes, we first examined Erk5 expression in various obese and diabetic animal models, such as C57BL/6J mice fed with 25-week HFD, two diabetic mouse models of db/db and ob/ob mice, and Rhesus monkeys with spontaneous metabolic syndrome12. The gene discussed is MAPK7; the disease is obesity due to melanocortin 4 receptor deficiency.