Staurosporine is a potent and cell-permeable inhibitor of a wide variety of protein kinases including protein kinase C (IC50 = 0.7 nM), protein kinase A (IC50 = 7 nM), and protein kinase G (IC50 = 8.5 nM). Staurosporine induces apoptosis in human neuroblastoma cells and chick embryonic neurons.