Figure 1. PP6R1 associates with DNA-PK in human cancer cells.

A. Cell extracts from irradiated DNA-PK proficient (M059K), and deficient glioblastoma cells (M059J) were immunoprecipitated with monoclonal α-DNA-PKcs antibody. Following SDS-PAGE, DNA-PKcs, PP6R1 and PP6c proteins were detected by immunostaining using specific antibodies or pre-immune serum. B. M059K cells were irradiated with 5 or 10 Gy, or sham-treated (0 Gy). One hour after radiation, the cells were lysed and cytoplasmic and nuclei were prepared. Nuclei were subjected to immunoprecipitation with DNA-PKcs antisera. C. Immunoblots of the nuclear fractions were quantified by densitometry. Standard error bars represent the mean of three independent experiments (± SD). The statistical significance of the differences between the amount of PP6c or PP6R1 in the nuclear fraction from irradiated cells, and in the nuclear fraction from non-irradiated control cells was (***, p<0.001) by Student T test.