Fig. 1.

AG490 inhibited IL-6-induced STAT3 activation. (A) AG490 (50 µM) suppressed tyrosine phosphorylation of STAT3 by IL-6 in a time-dependent manner without affecting STAT3 protein levels. AG490 or AG1478 (50 µM) was pretreated for the indicated times, and then stimulated with IL-6 for 15 min. (B) Quantitative results showing the change in pSTAT3 levels following AG490 treatment for the indicated times. (C) Luciferase promoter assay. RT4 cells were transfected with a GFAP promoter-luciferase reporter construct (GF1L). One day after transfection, the cells were pretreated with AG490 (50 µM) for 2 hrs, and then simulated with IL-6 for 6 hrs. The results are expressed as a relative value to the untreated controls. Data are the mean±S.E. from three independent experiments. (D) Temporal profile of tyrosine phosphorylation of STAT3 and JAK2 by IL-6. The cells were treated with IL-6 (50 ng/ml) for the indicated times, and then Western blot analysis was performed to examine tyrosine phosphorylation of STAT3 and JAK2. b-tub; beta-tubulin. ^*p<0.05.