FIGURE 1.
The STAT3 NH2-terminal domain is required for OSM-inducible transcription. A, the left panel is a Western immunoblot showing the endogenous STAT3 level in STAT3+/- MEFs (C4+/-) and the loss of STAT3 expression in STAT3-/- MEFs (L1-/-). In the right panel, the expression of transiently transfected V5-STAT3-FL and V5-STAT3-ΔNin STAT3-/- MEFs was measured by Western immunoblot with anti-V5 Ab. β-Actin was used as a loading control. B, STAT3-/- MEFs were transfected with the γ-FBG-LUC reporter gene together with different doses of V5-STAT3-FL or V5-STAT3-ΔN expression vectors and treated with OSM for 24 h prior to the reporter gene assay. Shown is mean and standard deviation (S.D.) normalized luciferase reporter activity. C, different doses of pCMVβ p300 were cotransfected with V5-STAT3-FL or V5-STAT3-ΔN together with γ-FBG-LUC reporter followed by OSM stimulation for 24 h. Data shown are means ± S.D. from three independent transfections. The data were analyzed by Student's t test. The luciferase reporter activities in V5-STAT3-FL-transfected MEFs were compared with those in V5-STAT3-ΔN-transfected MEFs using a Student's t test. *, p value <0.05; **, p value <0.01. N/A, not applicable.