CSB is important for the repair of oxidative stress-induced DNA lesions, as oxidative DNA lesions are increased in cells derived from Cockayne syndrome patients, and CSB has been found to functionally interact with 8-oxoguanine DNA glycosylase (OGG1) as well as apurinic/apyrimidinic endonuclease 1 (APE1), two enzymes critical for BER [23,24,25,26,27]. This evidence concerns the gene APEX1 and Cockayne syndrome.