IL13 and myocardial infarction: While there was no difference in scarring at 21 dpi, nor CM proliferation between genotypes, IL-4RαMacKO mice had significantly lower percent ejection fraction (%EF) compared with controls (IL-4Rαfl/fl or Cx3cr1Cre) (Figure 1J), indicating that, despite normal CM proliferation, lack of IL-13 signaling to cardiac macrophages has a deleterious effect on cardiac function after neonatal MI.