Figure 3: DNA double-strand break repair and DNA-PK as pharmaceutical target. Different steps may be used as targets in the NHEJ pathway. Recruitment of Ku70/Ku80 is essential for DNA-PK interaction (1) and activation; autophosphorylation of DNA-PK and phosphorylations of substrates (2) are involved in the repair process. Regulation of the DNA-PK activity is key and could be achieved via nphosphatases (4) or by inhibiting the previous steps. The output signals may coordinate different cell processes (5) such as the DNA damage response and some metabolic adaptations. (see text for details).