Effect of downregulation of Bax expression on 2B-induced apoptosis in HeLa cells. (A) Western blot analysis of Bak and Bax expression in HeLa cells that were transfected with siRNA against either Bak (siBak), Bax (siBax), or both (siBax siBak) as described previously (45). Cells transfected with nontargeting siRNA (siControl) were used as a control. At 48 h posttransfection, cell lysates were prepared, analyzed by SDS-PAGE, and immunoblotted with antibodies to Bax, Bak, or β-actin (internal control). (B) Analysis of the impact of 2B expression or EV71 infection on the viability of HeLa cells transfected with siRNA. Cells were transfected with the siRNAs described in Materials and Methods. At 48 h transfection, they were either transfected with pCMV-2B-Flag for another 48 h or infected with EV71 (MOI = 0.5) for 24 h and then subjected to cell viability analysis. EV71 (UV), UV-inactivated EV71. Control, siControl cells treated with DMSO. (C) Analysis of the impact of 2B on caspase-3-like activity in cell lysates of siRNA-transfected cells. Caspase-3 activity was determined as described in Materials and Methods. Control, siControl-transfected cells treated with 30 nM staurosporine. (D) Western blot analysis of Cyt c in the cytosol fraction. The cytosol fraction of cells was separated and immunoblotted with an antibody to Cyt c. Control, cells transfected with pCMV-Flag.