FIG. 1.

Stable cortactin knockdown in 11q13-amplified HNSCC cells decreases S-phase population. (a) Western blot analysis of cortactin expression in cortactin knockdown cells and in cells reconstituted with shRNA-resistant myc-tagged murine cortactin (mCortactin). (b) The effect of cortactin knockdown on the S-phase population in asynchronous cells. Following a 2-h pulse with BrdU, cell cycle analysis was performed using anti-BrdU and propidium iodide staining and flow cytometry. Data represent mean ± standard error from three independent experiments. *, P < 0.05. (c) The effect of cortactin knockdown on cell cycle progression following a G₀/G1 phase block. FaDu cells were synchronized into G₁ phase by serum starvation and hydroxyurea treatment and then released into complete medium for 6 h, with the addition of BrdU for the final 2 h. Representative data for BrdU uptake and PI staining are shown. (d) Effect of cortactin knockdown on S-phase entry for synchronized cells. The histogram indicates the S-phase population from experiments outlined in panel C. Data represent the mean ± standard error from three independent experiments. *, P < 0.05.