We have previously reported that actin cleavage activity (ACA) by interleukin 1beta-converting enzyme (ICE) family protease was elevated during anticancer drug-induced apoptosis in human leukemia U937 cells. In this study, the involvement of ACA in the drug-induced apoptosis in solid tumor cells was investigated. Human ovarian carcinoma OVCAR-3 cells undergo apoptotic cell death when cells are treated with chemotherapeutic agents such as cisplatin and etoposide. The induction of the actin cleavage activity accompanied the development of apoptosis. ICE/ced-3 family protease inhibitors such as Z-VAD-CH2DCB and Z-EVD-CH2DCB at 100 microg/ml prevented both the emergence of ACA and the morphological change, characteristics of apoptosis, in cisplatin-treated OVCAR-3 cells. The ACA in apoptotic OVCAR-3 cell lysate was greatly adsorbed by antibody against CPP-32, an ICE family protease. Furthermore, the immunoprecipitated CPP-32 from OVCAR-3 lysate could cleave actin to generate a 15-kDa fragment, as did the apoptotic OVCAR-3 cell lysate, indicating that CPP-32 is a major protease responsible for the ACA. The activation of CPP-32 in the drug-treated cell lysate was verified with Western blot analysis. Our present results indicate that CPP-32, an actin cleavage ICE/ced-3 family protease, could be a common mediator involved in the process of chemotherapy-induced apoptosis of cancer cells.