RT4 cells were incubated for 4 hr in transfection medium (control), with PPCat-siNT (100 nM) or PPCat-siSurvivin (100 nM), followed by 2 hr treatment without or with MMC in complete medium, and then processed for short term MTT assay (cytotoxicity measured at 48 hr post-treatment, Panel A), or the long term clonogenic assay (cytotoxicity measured at 23 days post treatment, Panel B). For Panel A, data are mean+1 SD (n=3 experiments, with triplicate samples per experiment). Some SD values are smaller than the symbols. For Panel B, data are mean+1 SD (n=3 experiments, triplicate samples per experiment). Ctl: control. –si: no siRNA, siNT: nontarget siRNA, siSur: survivin siRNA. *p<0.05 compared to untreated control (i.e., no MMC, no siRNA). **p<0.05 compared to untreated control as well as single agent MMC at same MMC concentration (i.e., no siRNA or MMC+siNT).