Cell cycle checkpoint activation and DNA repair pathways govern genomic stability after genotoxic
stress. Genotoxic insult results in activation of an interwoven network of DNA damage checkpoints and
DNA repair pathways. Post-translational modifications on a number of proteins involved in both
checkpoint activation and DNA repair play an important role in this cellular response. Genotoxic stress
can induce a wide variety of DNA lesions. Among these DNA alterations are double-stranded breaks and
single-stranded DNA gaps. Repair of these DNA alterations requires damage recognition and resection.
Here we discuss how DNA repair and DNA damage checkpoints cooperate and deal with DNA damage.
Processing of DNA lesions by structure-specific nucleases results in DNA–protein intermediates, which
form the basis for checkpoint activation and DNA repair. Post-translational modifications like
phosphorylation and ubiquitination modulate the DNA damage response in a spatial and temporal
manner. Cell cycle-dependent regulation additionally plays a key role in the regulation of both DNA
repair and checkpoint activation. We highlight recent advances in in vivo imaging that greatly expand
our knowledge on the relationships between DNA damage checkpoints and DNA repair.