IL-9–induced M-Ras expression in TS2 cells expressing wild-type or mutant hIL-9R. (A) Electromobility shift assay using a STAT-binding oligonucleotide. TS2 transfectants were stimulated for 10 minutes with IL-2, mIL-9, or hIL-9 (which does not bind the endogenous murine receptor) and nuclear extracts were prepared, and the electromobility shift assay was performed with the GRR oligonucleotide as described in Materials and Methods. (B) Northern blot analysis of M-Ras expression. The same cells were cultured for 48 hours in the presence of 200 U/mL of either IL-2 or murine IL-9, or 500 U/mL of human IL-9. Northern blots were prepared with 10 μg of total RNA and hybridized as described in Fig 1.