Fig. 1

Homologues recombinant DNA repair system. The overall process starts with the recognition of the DSB region by the Mre11-RAD50-Nbs1 (MRN) complex. Next, ATM phosphorylates γH2AX, MDC1, and RNF8, which subsequently initiate the formation of BRCA1–abraxas–RAP80 complex. Later, BRCA1 via cooperating with MRN forms a complex with CtIP, to promote 5′-end resection in the early steps of the synthesis-dependent strand annealing (SDSA) pathway of HR. BRCA1 interacts with PALB2 and BRCA2 to recruit RAD51, an essential mediator in the HR repairing pathway. The formation of BRCA1- PALB2- BRCA2 complex is relying on CHK2-mediated phosphorylation of S988 on BRCA1