Different apoptotic responses to chemotherapeutic agents according to Livin expression. (A) The proportion of patients with unfavorable day 7 bone marrow response (leukemic blasts ≥ 25%) was significantly lower in patients with Livin expression compared with patients without Livin expression (P < .001). (B) In the cytotoxicity assay to evaluate the ex vivo susceptibility of leukemic blasts to apoptotic stimuli provided by methylprednisolone, the percentages of surviving leukemic blasts after 24, 48, and 72 hours of culture were significantly lower when the leukemic cells expressed Livin mRNA. Graph shows means and SEM. (C) In the cytotoxicity assay, both full-length Livin protein (α- and β-isoform) and the cleaved form of Livin protein were persistently observed in the leukemic cells with Livin expression. The intensities of caspase 3 and PARP proteins increased as the apoptotic process continued.