['Apoptosis is mediated by many kinds of enzymes such as caspases, DNase and protein kinases. Recently, ATPase has been shown to be involved in the apoptotic system, but its role is not fully understood.', 'We investigated the effect of 8 species of ATPase inhibitors on actinomycin D plus colcemid-induced apoptosis in human megakaryoblastic leukemia CMK-7 cells by monitoring caspase-3 activation and DNA cleavage.', '2,3-Butanedione monoxime (BDM), lansoprazole, cyclopiazonic acid, geldanamycin and radicicol suppressed the apoptosis. Among these compounds, geldanamycin was the strongest suppressor of both caspase-3 activation and DNA cleavage. Furthermore, Western blotting showed that radicicol suppressed the proteolytic cleavage of procaspase-9 more strongly than BDM, lansoprazole or cyclopiazonic acid.'] Do aTPase inhibitors suppress actinomycin D-induced apoptosis in leukemia cells?