TCR/CD28-induced IFN-γ expression is decreased in p38α^Y323F T cells. (A) Wild-type (solid line) and p38α^Y323F (dashed line) T cells were stimulated as indicated for 48 hours and IFN-γ and IL-2 expression were detected by intracellular staining (A) or ELISA (B). (C) TNF-α expression was detected by intracellular staining in T cells stimulated with α-CD3/CD28 for 48 hours. (D) T cells were treated with IL-12 plus IL-18 or PMA/Iono for 48 hours, and then IFN-γ production was analyzed by intracellular staining. Shaded histograms present stimulated wild-type cells stained with matched isotype control antibody only. One of 3 independent experiments is shown.