The fibrotic area was 59.50 ± 1.4% and 56.64 ± 5.6% in MI group and GFP group, respectively, and Id2 treatment reduced the fibrotic size to 33.63 ± 3.7% (P < 0.05) (Figures 3A–C and Supplementary Table 3). Here, ID2 is linked to myocardial infarction.