ZZM-1220 is a histone lysine methyltransferase G9a/GLP covalent inhibitor with IC50s of of 458 nM and 924 nM, respectively. ZZM-1220 inhibits H3K9me2 in cells and significantly induces apoptosis of triple-negative breast cancer (TNBC) cells and blocks the cell cycle in the G2/M phase[1].