F Measurement of DNMT3A-ADD thermodynamic stability upon ATO or AsPh3 treatment. Purified DNMT3A-ADD was mixed with ATO or AsPh3 at the indicated ratios in 20 mM HEPES (pH 7.5) for 1 hour. Chemical structure of AsPh3 is shown. Melting curves were measured by DSF (upper panel), and the calculated ΔTm values are shown (lower panel). 