ALKBH2 dioxygenase activity assay 1 ug of ssDNA oligos (5’-AAAGCAG(1mA)ATTCGAAAAAGCGAAA-3’) was incubated with 0 ug, 0.5 ug, 1 ug, 2 ug, 4 ug of ALKBH2 in 50 ul reaction system including 50 mM HEPES-NaOH pH 8.0, 50 μM Fe(NH4)2(SO4)2, 1 mM 2-oxoglutarate, 2 mM ascorbate and 1 mM TCEP for 30 min at 37°C. Then ssDNA oligos were annealed with equimolar of non-methylated complement strand followed by 1 ug EcoRI digestion for 45 min at 37°C. 1/4 reaction products were run on a 20% Native PAGE gel and stained by ethidium bromide.