Notes: KSQ-4279 is an inhibitor of ubiquitin-specific protease 1 (USP1; IC50 = 21.1 nM).{72526} It reduces the viability of H1299 non-small cell lung cancer (NSCLC) cells when used at a concentration of 500 nM. KSQ-4279 (1 µM) induces cell cycle arrest at the S phase in MDA-MB-436 breast cancer cells.