Phthalazinone pyrazole is a potent, selective, and orally active inhibitor of Aurora-A kinase with an IC50 of 0.031 μM. Phthalazinone pyrazole can arrests mitosis and subsequently inhibit tumor growth via apoptosis of proliferating cells. Phthalazinone pyrazole suppresses the epithelial-mesenchymal transition (EMT) during the differentiation of hepatocyte-like cells (HLCs) from human embryonic stem cells.