IL-21 activated Jak1, Stat3, and Erk1/2, but not Stat1 or NF-κB.

(A) pYpY1022/1023 Jak1 was detected by Western blotting in the cell line OH-2 after stimulation with IL-6 (1 ng/mL) or IL-21 (40 ng/mL) for 5 and 20 minutes. The same pattern was found in IH-1. (B) pY701 Stat1 and pY705 Stat3 were detected by Western blotting in the cell line OH-2 after stimulation with IL-6 or IL-21 for 10, 20, or 60 minutes. The filter was reblotted for total Stat3. The same pattern was found in IH-1 cells. (C) pT202/pY204-Erk1/2 was detected by Western blotting in the cell line IH-1 after stimulation with IL-6 or IL-21 for 20 minutes. (D) NF-κB activity was detected by ELISA in the cell line OH-2 after stimulation with IL-6 (1 ng/mL), IL-21 (50 ng/mL), or TNF (10 ng/mL). Similar results were obtained in the cell line IH-1.