ERCC1 and xeroderma pigmentosum: A. thaliana plants mutated in XPF (xeroderma pigmentosum group F-complementing) and ERCC1 (excision repair cross-complementation group 1) orthologs that form a structure-specific endonuclease essential for nucleotide excision repair (known as AtRad1 and AtERCC1), develop normally and show wild-type telomere length.