FIG. 8.
Time course of Cdk2 inactivation and Cdk2-p27Kip1 complex formation in MAb 4D5-treated BT474 cells. BT474 cells were seeded and treated with MAb FRP5 or MAb 4D5 as in Fig. 2. At the times indicated, cell extracts were prepared and immunoprecipitated with Cdk2-specific or cyclin E-specific antibodies followed by in vitro histone H1 kinase assay (A). Additionally, the levels of p27Kip1 and Cdk2 protein in the same extracts were either analyzed directly by immunoblotting (WB) or after immunoprecipitation (IP) with Cdk2-specific antibodies (B). Untreated cells (t = 0) and cells treated with MAb FRP5 for 48 h were included as controls. Cdk2 kinase activity is expressed as percentage of control (t = 0) cells.