CBP depletion increases the survival of neuroblastoma cells after irradiation. (A) SH-SY5Y cells were transfected with control siRNA or CBP specific siRNA. Two days after transfection, the cells were irradiated at various doses of irradiation. Immediately after irradiation, cells were plated. One week after plating, the colonies were fixed with glutaraldehyde (6.0% v/v), stained with crystal violet (0.5%w/v), and counted using a microscope. The results are expressed as the percentage of the number of colonies (Mean±SD, N=3) compared to the number of colonies of IR-treated without siRNA transfection. (B) SH-SY5Y cells were transfected with a Ku70 K539/K542R expression vector. Two days after transfection, the cells were treated with various doses of irradiation as indicated. One day after irradiation, the cell viability was determined by MTT assay. Results are expressed as the percentage of viable cells compared with un-irradiated control cells (Mean±SD, N=3).