Staurosporine (STS) is a potent PKC inhibitor for PKCα, PKCγ and PKCη with IC50 of 2 nM, 5 nM and 4 nM, less potent to PKCδ (20 nM), PKCε (73 nM) and little active to PKCζ (1086 nM) in cell-free assays. Also shows inhibitory activities on other kinases, such as PKA, PKG, S6K, CaMKII, etc. Phase 3.