FIG. 4.
Effect of the interaction of STP-A11 with Stat3 and Src on the efficient activation of Stat3 transcriptional activity. 293T cells were transfected with a Stat3 luciferase reporter vector (pLuc-TKS3) and an expression vector containing wt STP-A11 or the Y115A, D1, D2, D3, or Y115A/D1 mutant in the presence or absence of the Src expression vector. At 48 h posttransfection, cells were harvested for measurement of luciferase activity. Transfection efficiency was normalized with the β-galactosidase reporter vector pGK-βgal. Results are averages from three independent experiments. Error bars, standard deviations. Gels at the bottom show expression of STP-A11, its mutants, and Src in whole-cell lysates.