Fig. 2. Increased STAT3 activation levels in STAT3-C-transfected clones. A representative SCCHN cell line (UM-22B) was stably transfected with STAT3-C. A, coimmunoprecipitation of representative clones showing FLAG expression in STAT3-C clones but not in controls. Cells were immunoprecipitated with anti-FLAG M2 monoclonal antibody followed by immunoblotting with the same antibody. B, immunoblotting of representative clones showing higher phospho-STAT3 expression in STAT3-C clones compared with vector-transfected control clones. C, EMSA showing higher constitutive STAT3 activation levels (SIF-A represents STAT3 homodimers) in STAT3-C clones compared with vector-transfected control clones.