FIGURE 3.

MKP7 inhibiting Th17 effector function is dependent on ERK. (A) Naive CD4⁺ T cells from WT and MKP7 chimeras were activated by anti-CD3 plus anti-CD28. Cells were lysed at the indicated time points. Cell extracts were resolved on SDS-PAGE gels and transferred to nitrocellulose membranes. Blots were probed with anti–p-ERK, anti–p-JNK, anti–p-p38, anti-ERK, anti-JNK, anti-p38, or anti-actin. (B) ERK2/pTpY was incubated with MKP7 or MKP3 at 25°C for 1 h, followed by Western blot analysis using the indicated Abs. The lower panel of the SDS-polyacrylamide gel (Coomassie stained) shows the amounts of purified ERK2/pTpY used in the experiment. (C) WT and KO naive CD4⁺ T cells were differentiated into Th17 cells in the presence of vehicle or indicated concentrations of U0126. Differentiated cells were activated with PMA and ionomycin for intracellular cytokine staining. WT and MKP7 KO T cells were differentiated into Th17 cells and stimulated with anti-CD3 Abs. IL-17, IL-17F, and RORγt gene expression were determined by qPCR (D), and IL-17 and IL-17F production were measured by ELISA assay (E). Data are representative of three independent experiments. **p < 0.01.