Chaetocin is a fungal metabolite and potent histone methyltransferase inhibitor, exhibiting IC50 values of 0.8 µM, 2.5 µM, and 3 µM against dSU(VAR)3-9, mouse G9a, and DIM5, respectively. It is widely used in epigenetics research to probe histone methylations role in gene silencing, cancer, and differentiation in both cellular and animal models.