Fig. 1. Reduced cell growth upon RNAi knockdown of Ku80. (A) HeLa cells treated with either transfection agent (control), a Ku80-targeting siRNA (Ku80-siRNA) or an siRNA with scrambled sequence (scr-siRNA) were grown for 24, 48, 72 and 96 hours. Untreated cells were also included as a control. Whole cell extracts were prepared at each time point and immunoblotted for Ku80. Actin was used as a loading control. (B) Staining of DNA with DAPI (blue) and anti-Ku80 (red) by immunofluorescence 96 hours after transfection with scr-siRNA or Ku80-siRNA. (C) Quantification of Ku80 levels in each sample shown in A. Values are expressed as relative optical density (ROD) compared to the untreated cells and represent the average of three experiments and one standard deviation (s.d). (D) Representative phase-contrast microscopic images of control, scr-siRNA-transfected and Ku80-siRNA-transfected cells at the indicated times after transfection. (E) Growth curves of the cells shown in D during the time-course of the Ku80 RNAi knockdown. Values represent the mean number of cells and the error bars are equivalent to 1 s.d.