FIGURE 5.

st and cyclin E cooperate to stabilize the cyclin H-CDK7 complex. A, formation of cyclin H-CDK7 complexes was analyzed via immunoprecipitation (IP) of lysates of BJ-hTERT cells transduced with the indicated adenoviruses or stimulated with serum followed by Western blot analysis (WB) with the indicated antibodies. B, CAK-associated kinase activity was measured in CDK7-immunoprecipitates from protein lysates obtained from the indicated treated cells. Kinase-dead GST-CDK2 was used as exogenous substrate. CAK activity was detected via Western blot analysis with a phosphospecific antibody to CDK2 phosphorylated on Thr-160.