CHEK1 and renal fibrosis: Under UUO injury, the levels of hypoxia in the obstructed kidneys increases, leading to the upregulation of FAT10 in RTECs; overexpression of FAT10 can stabilize USP7 by antagonizing the ubiquitination of USP7, resulting in increased levels of CHK1, which subsequently induces G2/M cell cycle arrest, triggering profibrotic TGF-β- and CTGF-mediated renal fibrosis.