By virtue of the epicardial WT1-CreER lineage tracing line, one would find that there is an increase in the adult endogenous WT1-derived cells following myocardial infarction, but such a slight increase is insufficient to improve heart function after injury; moreover, the WT1-derived cells are mostly cardiac fibroblasts [7,42]. Here, WT1 is linked to myocardial infarction.