DNA damage can be directly reversed by dealkylation (Mitra and Kaina 1993). Three enzymes play a major role in reparative DNA dealkylation: MGMT, ALKBH2 and ALKBH3. MGMT dealkylates O-6-methylguanine in a suicidal reaction that inactivates the enzyme (Daniels et al. 2000, Rasimas et al. 2004, Duguid et al. 2005, Tubbs et al. 2007), while ALKBH2 and ALKBH3 dealkylate 1-methyladenine, 3-methyladenine, 3-methylcytosine and 1-ethyladenine (Duncan et al. 2002, Dango et al. 2011).