The role of IL-6 as an initiator of the HWF effect on HN-7 cells. (a) Inhibition of STAT3 phosphorylation by tocilizumab. HN-7 cells were grown with 10% HWF, HS, or FBS and the indicated concentrations of tocilizumab. Phospho-STAT3 was analyzed by western blotting (upper panel) and quantified in relation to the loading control (lower panel). (b) The effect of tocilizumab on migration analyzed by the scratch assay (N=16). (c) Stimulation of migration by IL-6. HN-7 cells were analyzed in the presence of 10% HS or FBS and the indicated concentrations of IL-6 and tocilizumab (N=16). (d) The effect of tocilizumab on HWF-supported cell proliferation analyzed by SRB (N=10). Error bars represent SEM. (e) The expression of IL6Rα in HNSCC cell lines. Cell lysates (10 μg protein per lane) from cells grown with 10% FBS were analyzed by western blotting with an anti-IL6Rα antibody. Specific binding was determined using a 100-fold molar excess of an antibody blocking peptide. Relative expression of IL6Rα normalized to protein loading control is shown in the lower panel.