Cell-permeable. A DNA topoisomerase I inhibitor. Unlike Camptothecin (Cat. No. 1039), β-lapachone does not stabilize the cleavable complex, indicating a novel mode of action. Induces apoptosis in HL-60 and human prostate cancer cells via a p53-independent mechanism and blocks the cell cycle at G0/G1. Also acts as a histone demethylase inhibitor selective to JMJ2DE (IC₅₀ =3.6 µM).