However, Runx1 expression significantly increased to 43% and 44% of cardiomyocytes within the BZ and infarct regions, respectively, at 1 day after MI, a time when whole-heart contractile dysfunction was also first observed (Figure 1A and 1B and Figure IV in the online-only Data Supplement). The gene discussed is RUNX1; the disease is myocardial infarction.