Figure 5: NHEJ pathway. When DSBs occur, the heterodimer Ku70/Ku80 recognizes the DNA ends and recruits the DNA-dependent protein kinase (DNA-PKcs). The complex of DNA-PKcs and his substrate Artemis processes the DNA ends preparing them for ligation by XRCC4-Ligase IV. The RAD50- MRE11-NBS1 complex seems to cooperate with the other enzymes, mostly Artemis and Ligase IV, to relegate the broken ends.