DNA excision repair protein ERCC-1is a protein in humans that is encoded by ERCC1 gene. ogether with ERCC4, ERCC1 forms the ERCC1-XPF enzyme complex that participates in DNA repair and DNA recombination. Many aspects of these two gene products are described together here because they are partners during DNA repair. The ERCC1-XPF nuclease is an essential activity in the pathway of DNA nucleotide excision repair (NER). The ERCC1-XPF nuclease also functions in pathways to repair double-strand breaks in DNA, and in the repair of “crosslink” damage that harmfully links the two DNA strands. Cells with disabling mutations in ERCC1 are more sensitive than normal to particular DNA damaging agents, including ultraviolet (UV) radiation and to chemicals that cause crosslinking between DNA strands.