Notably, Parkin, the E3 ubiquitin ligase that plays a crucial role in the ischemic response during the early phase of myocardial infarction by enhancing degradation of damaged mitochondria via a specific form of autophagy termed mitophagy24–26, was markedly induced as early as 1 h after myocardial ischemia, when an induction of FGF21 was clearly observed. Here, PRKN is linked to myocardial ischemia.