PTGER4 and myocardial infarction: Accordingly, myocardial infarction induced cardiac hypertrophy was accompanied with significantly increased Stat-3 phosphorylation in wild type controls, but the increase of Stat-3 phosphorylation was absent in the heart from cardiomyocyte-specific EP4 knockout mouse, suggesting that EP4-Stat3 signaling is conserved in vivo and responsible for cardiac hypertrophy [71].