Inhibition of OSM-induced STAT-3 activation in human solid tumor cell lines by CK2 inhibitors. (A-C) Cell lysates were immunoblotted with the indicated antibodies. (A) CH235 human astroglioma cells were pretreated with TBB (50μM) for 2 hours and then stimulated with different concentrations of human OSM (0.5 and 1 ng/mL) for 30 minutes. The densitometric ratios of p-Y-STAT-3 versus STAT-3 were calculated. The value of lane 4 was compared with that of lane 3 (control, no inhibition), the value of lane 6 was compared with that of lane 5, and the percentage of inhibition was determined. γ2A-JAK2 human fibrosarcoma cells (B) and MDA-MB-231 human breast cancer cells (C) were pretreated with TBB (50μM) or emodin (50μM) for 2 hours and then stimulated with 0.5 ng/mL of human OSM for 30 minutes. The densitometric ratios of P-Y-STAT-3 versus STAT-3 were calculated. The values of lanes 3 and 4 were compared with that of lane 2 (control, no inhibition) and the percentage of inhibition was determined.