FIGURE 4.

Signaling in response to IL-2 in the γ318, γ323, truncation mutants and WT γC stably co-expressed with human IL-2Rβ in CHO cells. A, CHO cells were transfected with cDNA encoding human IL-2Rβ and various constructs of human γC (γC FL, γ318, or γ323); stable clones were selected. These cells were evaluated for expression of human γC and IL-2Rβ by FACS analysis as described (Fig. 1A). B, CHO cells expressing human IL-2Rβ and γC truncations were serum-starved for 24 h and then stimulated with human IL-2 (28 ng/ml) for 30 min. Cell lysates were prepared and immunoprecipitated with anti-STAT5 followed by WB with anti-phosphotyrosine (PY). WB membranes were then stripped and re-probed with anti-STAT5. Densitometric analysis of the WB films was performed as described under “Experimental Procedures.” These results are representative of two independent experiments.