The methylation of lysine residues on histones plays a central role in determining euchromatin structure and gene expression. The histone methyltransferase (HMTase) G9a can mono- or dimethylate lysine 9 on histone 3 (H3), contributing to early embryogenesis, genomic imprinting, and lymphocyte development. BIX01294 (hydrochloride hydrate) is a selective inhibitor of G9a HMTase (IC50 = 1.7 μM). It less effectively inhibits the HMTase G9a-like protein (GLP; IC50 = 38 μM) and has no effect on other known HMTases. BIX01294 has been used in combination with the calcium channel activator BayK8644 to facilitate the generation of induced pluripotent stem cells from somatic cells in vitro.