S100A9 and myocardial infarction: However, in models of MI induced by permanent coronary artery ligation, Marinković et al.78observed that S100A9−/− mice exhibited a decreased number of circulating monocytes and reduced infiltration of monocytes and macrophages into the heart on the 7th day after MI compared to WT mice, most importantly the numbers of repairing Ly6CloMerTKhi macrophages were reduced by approximately 50% in the myocardium of S100A9−/− mice; on the 21st day after MI, S100A9−/− mice showed worse cardiac function.