S39625, an E-ring camptothecin keto analogue, is a stable, potent, and selective topoisomerase I inhibitor without being substrates of drug efflux transporters. Nanomolar concentrations of S39625 induces intense and persistent histone gamma-H2AX. The chem
SFOM-0046 is an anticancer agent. SFOM-0046 arrests the cell cycle in S-phase and causes DNA replication stress, resulting in the phosphorylation of H2AX into gamma-H2AX.