APEX1 and glioblastoma: Here we summarize evidence that excision of N3-methyladenine (3-meA) by alkyladenine-DNA glycosylase (AAG), and repair of abasic sites by the apurinic/apyrimidinic endonuclease (Ap endo) activity of Ape1, also mediate GBM resistance to TMZ and other alkylators.