 The 5’ strand is then cleaved, either by XPF-ERCC1 or another endonuclease, forming a double-strand break (DSB), which can then be repaired by the homologous recombination pathway.DNA crosslinks generally cause loss of overlapping sequence information from the two strands of DNA.Therefore, accurate repair of the damage depends on retrieving the lost information from an undamaged homologous chromosome in the same cell.