Figure 2: NHEJ repair of DNA double-strand breaks (DSBs). DSBs can be produced by endogenous or exogenous damaging agents or during physiological processes as V(D)J recombination. Classic-NHEJ proceeds through the recruitment of Ku70/80 heterodimer at the ends of the DSBs, followed by the DNAPK catalytic subunit (cs) recruitment and activation. The DNA damage processing involves Artemis, through its DNA-PK interaction, or the Mre11 protein. Finally, a DNA polymerase (as Pol μ, λ) may synthesize new DNA ends before the ligation step, involving XLF, XRCC4 and DNA Ligase IV. The NHEJ factors and the repaired DNA are then released.