Figure 5: Wild-type PTP1B suppresses whereas C215S-PTP1B potentiates IL-6-induced STAT3 phosphorylation. Cells were transfected with adenovirus expressing enhanced green fluorescent protein (EGFP) or with adenovirus expressing wild-type (Figure 5A) or C215S PTP1B (Figure 5B) at multiplicity of infection values of 10—15 for 24 hours. After viruses were removed, cells were further incubated for 24 hours to allow time for PTP1B expression. Cells were then stimulated with 20 ng/ml of IL-6 for 30 min. p-STAT3 was checked with western blot by probing with anti-phospho-STAT3 (Tyr705). The membrane was stripped and reprobed with anti-STAT3 to serve as a loading control and incubated with anti-PTP1B to check the overexpression levels. Upper panels show the representative Western blot indicating the expression levels of PTP1B. Graphs show mean±SE of the ratio of phosphorylated STAT3 to total STAT3 from four independent experiments. Data were analyzed by using One-Way ANOVA followed by post hoc test. **P<0.01, compared to control, ##P<0.01, compared to IL-6 alone.