PTGER4 and myocardial infarction: Qian et al. (2008) generated cardiac specific EP4 deficiency, using site-specific recombination by the Cre recombinase method (Cre-loxP) to inactivate EP4 only in cardiomyocytes (CM- EP4 knockout [KO]), and showed that CM-EP4 KO mice are defective in their ability to activate Stat-3, presenting a worsening of systolic function after myocardial infarction injury.