POSTN and myocardial infarction: Periostin is secreted by CFs after MI or pressure overload injury (Shimazaki et al., 2008) and has been shown to improve infarct size and cardiac function in infarcted rat hearts by activating integrin- and phosphatidylinositol-3 kinase (PI3K) signaling, which subsequently induces cardiomyocyte cell-cycle re-entry (Kuhn et al., 2007), while periostin deficiencies inhibited myocardial regeneration after MI in neonatal mice (Chen et al., 2017).