Briefly, a positive feedback loop between miR-21a and hypoxia-inducible factor 1 subunit alpha (HIF-1α)/2α is mediated by the PTEN/Akt/mTOR pathway, which is involved in the reduction of epithelial apoptosis caused by ischemia-reperfusion-induced AKI (33). The gene discussed is PTEN; the disease is acute kidney injury.