FIG. 8.

Loss of Snk/Plk2 does not lead to progression into anaphase or G₁ phase after spindle inhibitors. (a) U2OS cells were transfected with control siRNA duplex or Snk/Plk2. siRNA duplex (300 nmol). Twenty-four hours after transfection, cells were treated with 1 μM paclitaxel or nocodazole (1.0 μg/ml). After a 24-h treatment, cells were harvested and stained for cyclin B1 expression. Cells were also stained with propidium iodide to measure DNA content. (b) Depicted in the chart is the percentage of cells with 4N DNA content that are cyclin B1 positive. Results are from one of several experiments each done in triplicate. (c) U2OS cells were transfected with control siRNA duplex or Snk/Plk2 siRNA duplex (300 nmol). Thirty-six hours after transfection, cells were treated with 1 μM paclitaxel. After 12 h, equal amounts of U2OS cell lysate were harvested and immunoprecipitated with mouse monoclonal anti-cyclin B1 antibody and subjected to Western blot analysis or an in vitro protein kinase assay using histone H1 as a substrate. Lysates were immunoblotted for cyclin B1 and cdc2.