Figure 4.

IL-4 deprivation induces JNK2 activation. Cell lysates from control or IL-4-deprived cells (1 × 10⁷) were immunoprecipitated with anti-JNK1 or -JNK2 antibody. JNK1 and JNK2 immune complexes were assayed by phosphorylating the c-Jun-GST substrate in the presence of [γ-³²P]ATP. Phosphorylated proteins were separated in SDS-PAGE and visualized by autoradiography. Densitometric analysis of JNK2 activity is shown below the autoradiography. As an internal control of c-Jun-GST protein loading in the reaction, JNK2 kinase activity measured in the presence of [γ-³²P]ATP was separated by SDS-PAGE, transferred to nitrocellulose, and probed with anti-c-Jun antibody. Similar results were obtained in three independent experiments. Molecular mass markers are shown.