FIGURE 6.

Signaling responses of CHO cells expressing human IL-4Rα and either γC (WT type I CHO) or chimeric receptor γC/IL-13Rα1 to IL-4 and IL-13. A, CHO cells were transfected with human IL-4Rα and either WT γC or γC/IL-13Rα1, and stable clones were selected. Expression of human γC and IL-4Rα on the surface of the indicated clones was evaluated by FACS as described (Fig. 1A). B, stable CHO cell clones expressing human IL-4Rα and either WT γC (WT Type I) or γC/IL-13Rα1 were serum-starved for 4 h and then either stimulated with human IL-4 (4) or human IL-13 (13, 5 ng/ml) for 15 min or were not stimulated with cytokine (0). Tyrosine phosphorylation of IRS-2 and STAT6 was analyzed as described (Fig. 1B). Phosphotyrosine blots were then stripped and re-probed for total IRS-2 and STAT6. Representative films from four independent experiments with one wild-type clone and two different chimeric clones are shown. C, densitometric analysis of the WB films was performed as described under “Experimental Procedures.” The amount of phosphoprotein is graphed as the fold induced above unstimulated cells. n = 5 (WT type I) and n = 7 (chimeric receptor), *, p < 0.05; n.s., not significant.