UNC0631 is a potent and selective inhibitor of G9a activity in vitro (IC₅₀ = 4 nM) and G9a/GLP-mediated dimethylation of histone 3 on lysine 9 in MDA-MB-231 cells (IC₅₀ = 25 nM). It potently inhibits G9a/GLP activity in a variety of cancer cell lines as well as in the human fetal lung IMR-90 cell line. Also displays excellent separation of functional potency versus cell toxicity.