IRS1 and myocardial infarction: When mRNA encoding dominant-negative mutants of the Igf1 receptor and insulin receptor substrate 1 (Irs1) were applied to the heart surface of adult mice as a gel to inhibit Igf1 signaling in epicardial cells, it reduced the expression of adipogenic markers as well as the fraction of hearts with epicardial adipose tissue 28 days after MI.