MAPK3 and Interstitial cardiac fibrosis: We previously reported that a high salt intake enhanced cardiac expressions of prorenin, renin, and (pro)renin receptor [(P)RR] as well as cardiac angiotensinogen and angiotensin II AT1 receptor, and activated their downstream signals ERK1/2, TGF-β1, p38MAPK, and HSP27, leading to the acceleration of cardiac interstitial fibrosis, perivascular fibrosis, and cardiomyocyte hypertrophy and to the deterioration of the cardiac function in spontaneously hypertensive rats (SHRs) [3].