Figure 1.

IL-6 and sIL-6R activate STAT3 in human neuroblastoma cells. A., The presence of phosphorylated pY⁷⁰⁵ STAT3 and STAT3 was detected by Western blot analysis in total cell lysates from 8 neuroblastoma cell lines. When indicated, cells were treated with IL-6 (10 ng/ml), sIL-6R (25 ng/ml). Lysates were obtained 30 minutes after treatment. The data are representative of 2 to 3 separate experiments showing similar results. B, The presence of STAT3 and pY⁷⁰⁵ STAT3 in cultured CHLA-255 (left panel) and CHLA-90 (right panel) cells untreated or treated for 30 minutes with IL-6 alone or with sIL-6R as described above was examined by immunocytofluorescence. Arrow: cytoplasmic STAT3. Arrowhead: nuclear pSTAT3. (Scale bar = 20 µm).