Expression of IL-4R subunits and STAT6 activation induced by IL-4 in human H-RS cell lines. (A) Expression of IL-4Rα chain on 5 H-RS cell lines was assessed by flow cytometry using phycoerythrin-conjugated anti–IL-4Rα monoclonal antibody (open curve). Staining with isotype-matched IgG served as control (shaded curve). (B) Cell lysates prepared from H-RS cell lines were subjected to immunoblotting analysis to assess the expression of IL-4R subunits. (C) Antibody to Tyr-641–phosphorylated STAT6 or whole STAT6 proteins was reacted with membranes with cell lysates from H-RS cells stimulated with or without IL-4.