SBE13 is a potent and selective Plk1 inhibitor, with an IC50 of 200 pM; SBE13 poorly inhibits Plk2 (IC50>66 μM) or Plk3 (IC50=875 nM). PLK1|200 pM (IC50)|PLK3|875 nM (IC50) SBE13 significantly reduce cell proliferation and induce apoptosis in HeLa cells, with an EC50 of 18 μM. SBE13 (1-100 μM) shows no effect on Caspase 3/7 activity in NIH-3T3 cells. SBE13 (66 and 100 μM) does not change morphology after treatment of primary cells. SBE13 (10 and 100 μM) reduces pRb staining in primary cells, and this indicates a G0/G1 arrest. SBE13 (66 and 100 μM) increases levels of cyclin B1, phospho histone H3, Wee1, Emi1 and securin, and results in cleavage of Cdc27 in HeLa cells. SBE13 (10 and 100 μM) also induces apoptosis of HeLa cells.