Synergistic effect of NF-κB and STAT3 on metastatic potential of gastric cancer cells. Stable SNU-638 cells infected with either IκBαM retroviral vector or an empty (EGFP) vector were transiently co-transfected with either control siRNA (siCtrl) or STAT3 siRNA (siSTAT3). (A) Whole cell lysates (WL) and nuclear extracts (NE) were obtained 24 h after co-transfection and protein levels for pRelA, pSTAT3 and β-actin or TFIIB were measured by immunoblotting. (B) Effect of interaction of NF-κB and STAT3 on cell migration capacity was evaluated by wound-healing assay 48 h after scratching. (C) Effect of interaction of NF-κB and STAT3 on cell invasion ability was measured by invasion assay 48 h after cell plating. Results were calculated as percentages relative to controls. Each bar represents the mean ± SD (n = 4). * P < 0.05 and ** P < 0.005. (D) The protein expressions of E-cadherin, Snail and β-actin in SNU-638 cells were determined by immunoblotting after co-transfection of IκBαM and siSTAT3.