FIG. 10.
Effects of anti-ErbB2 MAb treatment on SKBR3 cell proliferation and the expression and activity of G1 regulators. SKBR3 cells were seeded as in Fig. 2. (A, Expt. 1; B and C) or at half the density (A, Expt. 2). After 24 h of incubation, PBS, MAb FRP5, or MAb 4D5 was added as in Fig. 2, and cells were treated as follows: (A) incubated for 4 days and trypsinized, after which total cell number was calculated; (B) incubated for 24 h, trypsinized, and treated with propidium iodide, after which cell cycle distribution was analyzed by flow cytometry; (C) incubated for 24 h, after which cell extracts were prepared and the protein levels of G1 regulators were evaluated by immunoblotting, or p27Kip1 association with Cdk2 complexes, and Cdk2 activity, was assessed through immunoprecipitation (IP Cdk2) of Cdk2 followed by immunoblotting for associated p27Kip1 protein or in vitro histone H1 kinase assay. Cdk2 activity is indicated as a percentage of that in control (PBS)-treated cells.