It phosphorylates a wide range of substrates in vitro, including Ku70/Ku80, which is translocated along DNA.     ///    "DNA-dependent protein kinase (DNA-PK), a holoenzyme that comprises the DNA-PK catalytic subunit (DNA-PKcs) and the heterodimer Ku70/Ku80, has a major role in non-homologous end joining-the main pathway in mammals used to repair double-strand breaks. "