(A) MDA-MB-231 cells were transfected with the indicated siRNA (each at 10 nM). The next day, cells were then treated with the indicated anti-cancer drug at various concentrations for 24 h, followed by MTT assays. (B) MDA-MB-231 cells were transfected with the indicated siRNA (each at 10 nM). The next day, cells were treated with the indicated anti-cancer drug (2 μM for celastrol; 150 μM for cisplatin; 50 nM for docetaxel) for 24 h, followed by caspase-3 activity assays **p < 0.005; ***p < 0.0005. (C) MDA-MB-231 cells were transfected with the indicated siRNA (each at 10 nM). The next day, cells were treated with the indicated anti-cancer drug (15 μM for cisplatin; 50 nM for docetaxel) for 24 h, followed by Western blot analysis. (D) MDA-MB-231 cells were transfected with the indicated siRNA (each at 10 nM). Migration (upper panel) or invasion (lower panel) assay was carried out. **p < 0.005.