Because of the unexpected results with the Chinese hamster DNA-PKcs proficient and deficient cells we investigated the phenomenon further in human malignant glioblastoma cells deficient in DNA-PKcs, M059J, and the DNA-PKcs overexpressing M059J-Fus-1 cells (hereafter called Fus-1 cells for simplicity) (Figure 1C). This evidence concerns the gene PRKDC and glioblastoma.