FIG. 3.

STAT3 is essential for LIF action. (A) TT cells were treated with conditioned media or LIF for 2 days and examined by Western blot hybridization for STAT3 expression. (B to D) TTSTAT3-DN cells or the control TTpcDNA3.1 cells were treated for 2 days with LIF and observed for changes in morphology (B), growth (C), and downregulation of RET expression (D). The presence of STAT3-DN was detected by Western analysis of the C-terminal FLAG tag. Data (mean ± standard error) are from a representative experiment performed in triplicate. P value is <0.0001 for STAT3DN-LIF compared to pcDNA3.1-LIF on a cell growth curve (one-way analysis of variance). Experiments were repeated at least three times with similar results. Experiments were also done with other independent stably transfected clones with similar results (data not shown).