Purity >98%. A-366 is a potent, peptide-competitive inhibitor of the lysine methyltransferase G9a (IC50 = 3.3 nM). It displays greater than 1,000-fold selectivity over 21 other methyltransferases. A-366 significantly reduces the cellular levels of dimethylation on histone 3 at lysine 9 (H3K9Me2) in PC3 cells without reducing total histone 3, H3K27Me3, or H3K36Me2. It also blocks the interaction of the methyl lysine reader protein Spindlin1 with H3K4me3 by binding with a Spindlin1 Tudor domain (Kd = 111 nM). See the Structural Genomics Consortium (SGC) website for more information.