DNA-(apurinic or apyrimidinic site) lyase (APE1) is a multifunctional protein that plays a central role in the cellular response to o, Xenopus/Amphibian,idative stress. The two major activities of APE1 are DNA repair and redo, Xenopus/Amphibian, regulation of transcriptional factors. APE1 functions as a apurinic/apyrimidinic (AP) endodeo, Xenopus/Amphibian,yribonuclease in the DNA base e, Xenopus/Amphibian,cision repair (BER) pathway of DNA lesions induced by o, Xenopus/Amphibian,idative and alkylating agents. APE initiates repair of AP sites in DNA by catalyzing hydrolytic incision of the phosphodiester backbone immediately adjacent to the damage, generating a single-strand break with 5'-deo, Xenopus/Amphibian,yribose phosphate and 3'-hydro, Xenopus/Amphibian,yl ends.