siRNA-mediated depletion of TLK1 delays cell cycle progression and causes prolonged G2/M arrest after exposure to IR.

<p>A. Cells were transfected with an siRNA directed against TLK1 and then synchronized at the G1/S, after which they were harvested at the indicated time-points post-release and stained with PI and a FITC-conjugated α-BrdU antibody. B. HeLa cells were transfected with an siRNA directed against TLK1 or plasmids encoding WT and T355A Rad9. Cells were synchronized at the G1/S border, released for 2hr, and then exposed to 10Gy IR and harvested at the indicated time-points post-treatment. Cell cycle distribution was analyzed by flow cytometry. C. The proportion of cells transfected with WT or T355A Rad9 in G2/M at 14hr and 20hr after exposure to 10Gy IR. Error bars indicate the standard error from three independent experiments. The asterisks denote a statistically significant difference between the G2/M populations comparing WT to T355A transfected cells (p=0.0092).