BMI1 and myocardial infarction: In this study, we investigated the potential role of Bmi‐1 on cardiac stem/progenitor cells by using Bmi‐1‐GFP‐knock‐in mice, in which GFP was expressed under the endogenous transcriptional regulatory elements of the Bmi‐1 gene, and the levels of Bmi‐1 expression in cells could be quantified by GFP fluorescence.3 We found that the subpopulations of cells with high expression of Bmi‐1 in heart tissue enriched in SP and Sca‐1‐positive cardiac stem/progenitor cells, and showed a significantly increase in number in response to myocardial infarction.