Nth endonuclease III-like protein 1(NTHL1) is one of the enzymes which act on a large number of oxidatively damaged DNA sites. NTHL1 has an apurinic and/or apyrimidinic endonuclease activity and a DNA N-glycosylase activity. NTHL1 acts on a damaged strand, 5’ from the damaged site and incises damaged DNA at cytosines, thymines and guanines.