FIGURE 2.

PP6c is not required for DNA-PK-R1 interaction. A, 293T cells were transfected with control (non-target) or PP6c siRNA (PP6c). Seventy-two hours post-transfection, lysates were subjected to Western blotting with the indicated antibodies. The levels of PP6c and R1 were quantified by densitometric analysis and normalized to actin. Values below the Western blot analysis are mean ± S.D. from three independent experiments. p < 0.005 for PP6c and p < 0.05 for R1. B, 293T cells were transfected with control or PP6c siRNA. Twenty-four hours post-transfection, both control and PP6c knockdown cells were transfected with the FLAG-R1 plasmid. Forty-eight hours post-transfection, FLAG-R1 was immunoprecipitated (IP) from the lysates of these cells using anti-FLAG antibody. The levels of input proteins (top three panels) and immunoprecipitated proteins (bottom two panels) were determined by Western blotting with the indicated antibodies. The relative amount of coprecipitated DNA-PK was quantified by densitometric analysis and compared with the amount of DNA-PK coprecipitated from cells transfected with non-targeting siRNA (second lane). Values below the Western blot analysis are mean ± S.D. from three independent experiments, difference not significant.