Selective inhibitor of PLK1 (IC50 values are 200 pM, 875 nM and 66 μM for PLK1, PLK3 and PLK2 respectively). Exhibits no effect on Aurora kinase A activity. Binds and stabilizes the inactive form of PLK1. Delays cell cycle progression, reduces cell proliferation and induces apoptosis in a range of human cancer cell lines. Transiently arrests cells cycle at G0/G1 in primary cells.