Tumor tissues were homogenized with protein extraction solution (PRO-PREPTM, Intron Biotechnology, Seoul, Korea), and lysed by 60 min incubation on ice. The tissue lysate centrifuged at 15,000 rpm for 15 min at 4°C. Equal amounts of proteins (40 µg) were separated on a SDS/12%-polyacrylamide gel, and then transferred to a polyvinylidene difluoride (PVDF) membrane (GE Water and Process technologies, Trevose, PA, USA). Blots were blocked for 1 h at room temperature with 5% (w/v) non-fat dried milk in Tris-Buffered Saline Tween-20 [TBST: 10 mM Tris (pH 8.0) and 150 mM NaCl solution containing 0.05% Tween-20]. After a short washing in TBST, the membranes were immunoblotted with the following primary antibodies: mouse monoclonal antibodies directed against p65 and p50 (1∶500 dilutions; Santa Cruz Biotechnology, Santa Cruz, CA), rabbit polyclonal antibodies directed against Bax and PARP (1∶500 dilutions; Santa Cruz Biotechnology), and against caspase-3, caspase-9, Bcl-2 and c-IAP-1 (1∶1000 dilutions; Cell Signaling Technology, Beverly, MA). The blots were incubated with the respective horseradish peroxidase-conjugated anti-rabbit or anti-mouse IgG (1∶4000 dilutions; Santa Cruz Biotechnology). Immunoreactive proteins were detected with the ECL detection system.