FN1 and myocardial infarction: In a rat model of coronary artery ligation, Casscells et al. found increased intracellular immunochemical staining for fibronectin in the necrotic myocytes within 4 h after MI, peaking in intensity at 48 h and declining after 72 h; viable myocytes did not show any fibronectin immunoreactivity at all stages of infarction [38].