COL1A1 and myocardial infarction: In a coronary artery ligation model of MI, in situ hybridization performed 7 days following ligation found 47% of EMR1 (i.e., gene for F4/80) expressing macrophages also expressed Col1a1 and 26% co-expressed Col1a1 and the myofibroblast marker Postn (82).