The phosphorylation of gp130 and STAT3 is down-regulated by Sant7 or an anti-gp130 mAb in the absence or presence of BMSCs.

INA-6 cells were cultivated without IL-6 (lane 1), with 2 ng/mL IL-6 (lanes 2 and 3), or with BMSCs (lanes 4 and 5), and treated either with Sant7 (50 μg/mL; A,B: lanes 3 and 5) or with a blocking anti-gp130 mAb (100 μg/mL; C: lanes 3 and 5) for 12 hours. The phosphorylation of gp130 was analyzed by Western blotting and staining of immunoprecipitated gp130 with an antiphosphotyrosine antibody (A). The phosphorylation of STAT3 after treatment with Sant7 (B) or an anti-gp130 mAb (C) was detected on Western blots with a mAb against phosphorylated STAT3 at residue Tyr705. Western blot analysis of unphosphorylated gp130 or STAT3 served as a loading control.