More importantly, administration of irbesartan significantly reversed ACE2 deficiency-induced increases in CVF, TGFβ1, CTGF, collagen I, collagen III and phosphorylated ERK1/2 and remarkably attenuated myocardial fibrosis and ultrastructure injury, likely driven by the elevation in PPARγ levels in ACE2KO mice. Here, MAPK3 is linked to Myocardial fibrosis.