Damage to the DNA resulting in double stranded breaks in the DNA (DSB) triggers the DNA damage response or DDR.This results in cell cycle arrest, associated with DNA Damage Response (DDR) pathways channeling repair enzymes to the damaged DNA histones.The presence of the DSBs is sensed by a multifunctional sensor complex (MRN).MRN complexes can bind to the exposed DNA ends directly and unwind the DNA ends in an ATP-dependent manner.