The genomes of all living organisms are extremely stable. DNA in the cell is replicated during cell division and passes all the genetic information to the next generation. It is essential for all living organisms to ensure proper functioning and propagation of their genetic information. Due to constant exposure of the genome to various endogenous and exogenous agents, however, the DNA becomes damaged leading to a large variety of DNA lesions.

Nucleotide excision repair (NER) is one of the main cellular reaction to DNA damage, contribu- ting to genomic stability. NER is a major cellular pathway that removes bulky DNA adducts and helix- distorting lesions, such as the UV-induced photoproducts cyclobutane pyrimidine dimers and 6–4 pyri- midine photoproducts. The heterogeneity of NER seems to be governed by the functional compartmen- talization of chromatin into transcriptionally active and inactive domains as well as by functional role of sequences within genes.