In accordance with previous findings, very few cardiomyocytes underwent proliferation under physiological conditions (Sham group, data not shown).30 No Ki67-positive cardiomyocytes were identified at various time points (24 h, 48 h, 7 days, 14 days, 28 days) in adult mice following infarction (MI group, data not shown). The gene discussed is MKI67; the disease is myocardial infarction.