FANCI and Fanconi anemia: USP1 regulates Fanconi anemia group D2 protein (FANCD2) ubiquitination which plays a vital role in the Fanconi anemia pathway of DNA crosslink repair.[114, 115] USP1 depletion increases voluntary monoubiquitination of FANCD2 and impairs accumulation of the Fanconi anemia core complex at DNA damage sites in a cell cycle‐dependent manner.[115] USP1 promotes multiple rounds of repair in the S phase by modulating the turnover of FANCD2‐ Fanconi anemia group I protein (FANCI) monoubiquitination at the damaged sites.