PRDM9 and acute lymphoblastic leukemia: To ensure that these drugs efficiently inhibit the histone methyltransferase activity of G9a in T-ALL, we first quantified the H3K9 methyl marks (me1-3) upon acid histone extraction and found homogenous levels of methylated residues in both NOTCH1 mutated and wild-type T-ALL cell lines (Fig. 3A).