Becatecarin is a water-soluble, diethylaminoethyl analog of the antineoplastic antibiotic rebeccamycin. It intercalates into DNA, stabilizing the DNA-topoisomerase complex. This results in the potent catalytic inhibition of both topoisomerases I and II, initiating DNA cleavage and apoptosis. Becatecarin, alone or in combination with other compounds, has anti-cancer as well as myelosuppressive effects in vivo. It is also a transport substrate of the ATP-binding cassette (ABC) transporter ABCG2.