CDK1 Cyc B-IN-1 (Compound 5) is a potent inhibitor of the CDK1 Cyc B complex, demonstrating selectivity with an IC50 value of 97 nM. This compound induces apoptosis and G2 M cell cycle arrest, effectively halting cancer cell proliferation. Additionally, CDK1 Cyc B-IN-1 exhibits a wide-ranging cytotoxic effect on various cancer cell lines [1].