Kenpaullone shows much less effect on c-src (IC50, 15 μM), casein kinase 2 (IC50, 20 μM), erk 1 (IC50, 20 μM), and erk 2 (IC50, 9 μM). Kenpaullone acts by competitive inhibition of ATP binding, and the apparent Ki is 2.5 μM. Kenpaullone can inhibit the growth of tumor cells in culture (mean GI50, 43 μM) and causes altered cell cycle progression most clearly revealed under conditions of recovery from serum starvation. Kenpaullone demonstrates a wide range of biological utility, extending from maintenance of pancreatic β cell survival and proliferation to the induction of apoptosis in cancer cells.