ACTA1 and myocardial infarction: However, collagen expression was not profoundly altered by Ampkα1 deficiency in myocardial infarction and a specific effect on myofibroblast activation and α-Sma expression was observed [55] Impaired M2 macrophage activation similarly leads to impaired myofibroblast activation in myocardial infarction [56].