PLK2 and acute kidney injury: The percentages of nuclear Nrf2-, p21cip1-, and Plk2-positive cells were approximately 65.8%, 74.6%, and 64.2%, respectively, in cisplatin-treated NRK52E cells (Fig. 6f), indicating that cisplatin-induced AKI triggers the nuclear translocation of Nrf2, p21cip1, and Plk2.