Maintenance of genomic integrity is of fundamental importance to all living organisms. DNA is continuously challenged by genotoxic stress. To ensure genome stability, cells have evolved various pathways to sense DNA damage, activate cell cycle checkpoints and initiate DNA repair. In eukaryotic cells, DNA is packaged with histones and other accessory proteins into chromatin. Damage sensing proteins and DNA repair enzymes must deal with the highly compact and dynamic structure of chromatin. The focus of our research is to understand how DNA repair pathways operate in chromatin to remove DNA lesions. We are also interested in understanding how DNA damage sensing leads to cell cycle arrest or apoptosis.