Response of Molt4 cells to chemotherapy is altered by downregulation of target genes. (a) Molt4 cells transfected with securin, TOP2A, cyclin B1 or control shRNA constructs were incubated with increasing doses of etoposide for 24h followed by flow cytometric analysis for determination of percentage of annexin V-positive cells. (b) Transfection of control or survivin shRNA constructs into Molt4 cells followed by incubation with increasing doses of doxorubicin, etoposide, vincristine and L-asparaginase for 24–48h. Apoptosis was determined by flow cytometric analysis of annexin V-positive cells. Percentage of apoptosis is graphed relative to control shRNA in the absence of chemotherapeutic agent ±s.d. Each experiment was performed in triplicate (*P<0.01, **P<0.0001 comparing shRNA with control).