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 64 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.