Fig. 7. JNK and NFATc1 activation. (A) Extracts from T cells activated with anti-CD3 antibody either in the absence or in the presence of anti-CD28 antibody for 48 h were used to measure JNK activity (determined by the level of Ser63 phosphorylation of c-Jun in anti-JNK immunoprecipitates). These extracts were also blotted with anti-JNK to verify the levels of the enzyme. (B) In another set of experiments, T cells either WT or Par-4^–/– were stimulated as above and the amount of nuclear NFATc1 was determined by immunoblotting. (C) Parallel extracts were analyzed by immunoblotting using an anti-Par-4 antibody. Experiments shown are representative of another three with similar results.