Moreover, knockdown of p38 MAPK with its siRNA inhibited the phosphorylation of both p38 MAPK and AMPK (Fig. S28G−H), indicating that Erk1/2-p38 MAPK–AMPK pathway is also involved in FGF21-induced cardiac protection against T2DM. The gene discussed is MAPK3; the disease is type 2 diabetes mellitus.