Figure 4.

(A and B) IL-4-induced [³²P]FcγRI and [³²P]Iɛ binding to Stat6 isoforms. FDC-P2 or FDC-P2–Stat6 isoform transfectants were starved as indicated and then untreated or treated with IL-4 (500 ng/ml) for 20 min. Whole cell lysates were incubated with [³²P]FcγRI or [³²P]Iɛ for 15 min and assayed by EMSA (26). Binding activity was visualized by autoradiography. (C) Effect of Stat6 isoforms on FcγRI luciferase reporter transcriptional activation in the presence (solid bar) or absence (open bar) of IL-4. The relative luciferase activity of IL-4-stimulated NIH 3T3 cells (solid bar) is compared with unstimulated cells (open bar). The amount of transfected cDNA is indicated below. Endogenous Stat6 activation was identical in control pCEV29 transfected (10 μg) or nontransfected NIH 3T3 cells. Values shown are the mean ± SEM of three determinations.