Phosphorylation at site S727 drives STAT3 into the mitochondria (mtSTAT3) to participate in electron transport chain activity [28,29,30], while phosphorylation at site Y705 drives STAT3 into the nucleus, where it functions as a transcriptional activator and influences the pathophysiology of cardiomyopathy. The gene discussed is STAT3; the disease is cardiomyopathy.