Figure 2.

JNK is constitutively activated in TpM T cells. (A) Constitutive and PMA-induced JNK activation are not inhibited by BIM in TpM T cells. TpM T cells were pretreated with BIM for 1 hr as indicated and then stimulated for 15 min with PMA in the presence or absence of BIM. JNK was isolated from 1 mg of extract by absorption to GST-c-Jun(1–166) fusion protein immobilized on glutathione-agarose beads. JNK activity was monitored by measuring the phosphorylation of GST-c-Jun(1–166) in a solid-state kinase assay. Phosphorylated GST-c-Jun(1–166) was visualized by autoradiograph (Lower) and quantitated by phosphoimager analysis (Upper). (B) PMA-induced JNK activation in LN T cells is inhibited by BIM. LN T cells were stimulated with PMA for 15 min in the presence or absence of the inhibitor BIM, as indicated. JNK was isolated from 1 mg of extract, and JNK kinase analysis was performed as in A.