PTEN and Myocardial fibrosis: For example, miR-21 was found to enhance myocardial fibrosis by targeting the extracellular signal-regulated kinase (ERK)–mitogen-activated protein (MAP) kinase pathway via sprouty homolog 1 (SPRY1) (103) and the phosphatase and tensin homolog (PTEN)–AKT phosphorylation-dependent pathway (104).