FIGURE 1.

Pathways for DSB repair. The main steps of non-homologous end joining and homologous recombination repair mechanisms are represented. Homologous recombination can proceed through distinct pathways (holiday junction resolution, synthesis-dependent strand annealing (SDSA), break-induced replication (BIR) and holiday junction dissolution) all sharing identical initial steps. The cell cycle is a major determinant of the choice between the DSB repair mechanisms. While NHEJ is available throughout interphase, homologous recombination pathways are restricted to S/G2 phases of the cell cycle.