Inhibitors of methyl-lysine binding proteins. (A) The methyl-lysine-binding pocket of L3MBTL1 illustrating the aromatic cage that surrounds the dimethyl-lysine moiety in the H4K20me2 cocrystal structure (Valérie Campagna-Slater, SGC, PDB 2PQW). (B) Structure and inhibitory properties of UNC1215 versus a panel of methyl-lysine reader domains.