Figure 1.

Cell cycle-dependent response to DSB formation. Depending on the stage of cell cycle (A), the induction of DSB (B) will lead to distinct cellular ATM or ATR signaling responses and DNA repair pathways. While DNA-PK drives NHEJ repair without resection of DNA ends, the MRN-CtIP removes DNA-PK and HR can function and use sister chromatids as a template for DNA repair synthesis. (C) Upon some context, including HR defect, the MMEJ and SSA repair pathways can act on the resected single-stranded DNA. MMEJ can act as a backup for NHEJ in G1 phase.