FIGURE 3.

Specificity of kinases for Ser-707 phosphorylation of STAT6. A, purified GST-STAT6WT was incubated in the presence or absence of purified active JNK (lanes 1 and 2), p38 (lanes 3 and 4), ERK (lanes 5 and 6), or AKT (lanes 7 and 8). Products were separated on a 10% SDS-polyacrylamide gel, and analyzed by Coomassie staining (upper panel) or autoradiogram (lower panel). B, effects of JNK, p38, ERK, or AKT knockdown on Ser-707 phosphorylation of STAT6. siRNAs were transfected into HeLa cells, which were incubated with DMSO (control) or anisomycin (500 ng/ml) for 45 min. The levels of Ser-707 phosphorylation of STAT6 were observed as a mobility shift in Western blots. The arrow indicates a shifted band.