FIG. 5.
Upregulation of p57Kip2 contributes to decreased cell cycle progression in cortactin knockdown cells. (A) Western blot analysis of p57Kip2 and cyclin D1 expression. Control and cortactin knockdown cells were transiently transfected with the indicated siRNAs during the serum starvation step of the synchronization procedure. Cell lysates were subjected to Western blotting as indicated. Data presented are derived from an individual experiment although intervening bands have been removed for the sake of clarity. Data are also representative of at least three independent experiments. (B) Effect of p57Kip2 knockdown on cell cycle progression. Entry into S-phase after a 6-h release was determined by uptake of BrdU during a 2-h pulse. The incorporation of BrdU was measured by flow cytometry. Data shown represent the mean ± standard error of three independent experiments. *, P < 0.05.