Staurosporine inhibits a variety of kinases including PKA (Ki=7.0 nM), PKG (Ki=8.5 nM), MLCK (Ki=1.3 nM), PKC (Ki=0.7 nM) (1,2), CaMK (IC50=20 nM), tyrosine kinases (IC50=70 nM) and phosphorylase kinase (IC50=0.5 nM). Inhibition is via interaction with the ATP binding site. It induces PKC translocation and augments PMA-induced ornithine decarboxylase. Activates a Bcl-2-regulated apoptosis pathway. Staurosporine binds to the ATP binding domain. The IC50's for the various recombinant PKC isotypes a, b, g, d, e were 58, 65, 49, 325 and 160 nM, respectively, but it did not inhibit PKC-z. At 1 µM staurosporine induced apoptosis in CHO cells. It also inhibits topoisomerase II directly by blocking transfer of phosphodiester bonds from DNA to active site tyrosine.