GP130 production and activity in the patients’ primary fibroblasts. (A and B) GP130 levels in primary fibroblasts, as evaluated by flow cytometry. (A) Representative traces of GP130 expression in primary fibroblasts from P5 and a healthy control are shown, together with traces for the isotypic control. (B) The graph shows the MFI of GP130 in five independent controls, and two patients (P2 and P5). The bars and error bars for the patients represent the mean of a duplicate and the standard deviation, respectively. (C) Total protein was extracted from primary fibroblasts and subjected to immunoblotting with a mAb against GP130 (amino acids 365–619, clone E8). GAPDH was used as a loading control. Western blots representative of three independent experiments are shown. (D) Primary fibroblasts from P2 and P5 and three healthy controls (Ctl, only one shown) were stimulated (Stim) for 15 min with IL-6, IL-6/IL-6Rα, IL-11, LIF, OSM, and IFN-α or left unstimulated (NS), and the phosphorylation of STAT3 (pY705, top panel) and STAT1 (pY701, bottom panel) was then evaluated by flow cytometry. FACS plots representative of two independent experiments are shown.