Since STAT1 is widely expressed in various cells, we used MAC-2 as a macrophage marker to detect the expression of STAT1 and found that STAT1 was highly expressed in cardiac macrophages after MI, and the expression of STAT1 in Klf9–/– macrophages was lower 1 day post-MI and higher 3 days post-MI compared with the WT group (Figure 8, A and B, and Supplemental Figure 6D). This evidence concerns the gene KLF9 and myocardial infarction.