We digested mouse hearts 3 days after MI and subsequently stained the isolated cardiac cells with anti‐CD11b (a macrophage marker) and anti‐PDGFR‐α (a marker of fibroblasts/myofibroblasts) antibodies to collect macrophages and cardiac fibroblasts/myofibroblasts using a cell sorter (Fig. S3). The gene discussed is PDGFRA; the disease is myocardial infarction.