NF-κB DNA binding induced by IL-9 in cells expressing mutated hIL-9R. BW5147 cells transfected with the wild-type human IL-9R (BWh9R) or mutants of this receptor partially (BWmut6 and BWmut7) or totally (BWphe116) defective in STAT activation (see text) were stimulated with 100 U/mL human IL-9 for 24 hours or with the equivalent amount of mIL-9 as a positive control. Nuclear extracts were prepared and a mobility shift assay was performed using a³²P-labeled palindromic κB site. An Sp1 DNA binding site was used as a control for the even loading of proteins in each lane.