A PRMT5 inhibitor; inhibits methylation of peptides derived from histones H4 and H2A, SmD3, FUBP1, and HNRNPH1 by the PRMT5/MEP50 complex (IC50s = 5.9-19.7 nM); more than 4,000-fold selective for PRMT5/MEP50 over a panel of 20 methyltransferases; induces alternative splicing of MDM4 in Z-138, MCF-7, JM1, and DOHH-2 cells at 200 nM; increases p53 and p21 protein levels in Z-138 cells in a concentration-dependent manner; inhibits growth and SDMA methylation in several lymphoma and breast cancer cell lines; reduces tumor growth in a Z-138 mouse xenograft model at 25, 50, and 100 mg/kg twice per day