ON1231320 is a highly specific polo like kinase 2 (PLK2) inhibitor with an IC 50 of 0.31 µM. ON1231320 blocks tumor cell cycle progression in the G2/M phase in mitosis, causing apoptotic cell death. ON1231320, an arylsulfonyl pyrido-pyrimidinone, has antitumor activity In Vitro ON1231320 (Compound 7ao) has no inhibitory activity against PLK1, PLK3 and PLK4 (all IC 50 >10 µM). ON1231320 (0-5 µM; 24 hours) activates programmed cell death in human tumor cells. ON1231320 inhibits cell proliferation in 16 tumor cell lines (DU145, MCF-7, BT474, SK-OV-3, MIA-PaCa-2, SK-MEL-28, A549, U87, COLO-205, HELA, H1975, RAJI, U205, K562, GRANTA-519; IC 50 = 0.035-0.2 µM). ON1231320 does not appreciably inhibit tubulin polymerization. ON1231320 does not affect normal human fibroblasts. MCE has not independently confirmed the accuracy of these methods. They are for reference only. Apoptosis AnalysisCell Line: U2OS cells Concentration: 0-5 µM Incubation Time: 24 hours Result: Increased the activity of Caspases 3/7 in a dose-dependent manner. Induced apoptosis. In Vivo ON1231320 (Compound 7ao; 75 mg/kg; IP; alternate days (Q2D) for 20 days) results in significant inhibition of tumor growth . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Animal Model: 6-8 week old NCR nu/nu female mice with MDAMB-231 triple negative breast cancer cells Dosage: 75 mg/kg Administration: IP; alternate days (Q2D) for 20 days Result: Resulted in significant inhibition of tumor growth (86.5%) Form:Solid IC50& Target:PLK2 0.31 μM (IC 50 ) PLK1 >10 μM (IC 50 ) PLK3 >10 μM (IC 50 ) PLK4 >10 μM (IC 50 )