ACTA2 and myocardial infarction: However, recent studies on matrifibrocytes indicate that ACTA2 elevation may be transient; 2–4 days after MI injury, activated CFs begin to express αSMA, followed by 4–7 days after injury, activated CFs become myofibroblasts and display high levels of αSMA, eventually by day 10, these CFs further differentiate into matrifibrocytes resulting in loss of αSMA expression and halted the proliferation (Fu et al., 2018).