STAT3 and myocardial infarction: STAT3 participates in protection against myocardial infarction (MI), cardiac ischemia/reperfusion (I/R) injury, and peripartum cardiomyopathy (PPCM) by reducing apoptosis, increasing the expression of survival proteins, protecting mitochondrial respiration and metabolism, and delaying mitochondrial permeability transition pore (mPTP) opening.