Fig. 1

CD109 promotes IL6Rα stability and IL-6 induced phosphorylation of STAT3 in SCC cells. A, B A431, SCC9 wild-type (WT) cells and CD109 knockout (KO) cells were treated with IL-6 (20 ng/mL) for 30 min and the expression of CD109, IL6Rα and phosphorylation of the STAT3 (Y705) proteins were analyzed by Western blotting. Densitometric analysis of the data depicted in A and B are shown in supplementary data. C A431-WT and A431-CD109 KO cells were treated with IL-6 (20 ng/ml) for various time periods (0–4 h), and the levels of phospho-STAT3 (Y705) and total STAT3 were assessed by Western blot. β-Actin was used as a loading control. D Fluorescence microscopy showing the levels of phospho-STAT3 (Y705) (upper panels, green) and total STAT3 (lower panels, green) in A431-WT and A431-CD109 KO cells treated with IL-6 (20 ng/ml). Scale bar: 25 μm. E A431-WT and A431-CD109 KO cells transfected with IL6Rα siRNA or control siRNA and treated with IL-6 (20 ng/ml), and the expression of IL6Rα, CD109 and the levels of phospho-STAT3 (Y705) were analyzed by Western blotting. F A431 and SCC9 cells were treated without or with (20 ug) tocilizumab for 24 h and the expression of IL6Rα, CD109 and phosphorylation of STAT-3 (Y705) were analyzed by Western blotting. All results (A–F) are representative of at least 3 independent experiments. Significance was calculated using a student T-test. NS: Not significant, * P < 0.05, ** P < 0.01 and *** P < 0.0010