7-oxo Staurosporine is an antibiotic originally isolated from S. platensis with diverse biological activites. It inhibits PKC, PKA, phosphorylase kinase, EGFR, and c-Src in vitro (IC50s = 9, 26, 5, 200, and 800 nM, respectively). 7-oxo Staurosporine induces cell cycle arrest in the G2/M phase in human leukemia K562 cells with a minimal effective dose (MED) of 30 ng/ml. It is cytotoxic to P388 mouse leukemia cells that are resistant and susceptible to doxorubicin . 7-oxo Staurosporine inhibits growth of the mycelial, but not yeast form of C. albicans, C. krusei, C. tropicalis, and C. lusitaniae (MICs = 3.1-25 μg/ml). It increases sphingomyelin synthesis in CHO-K1 cells when used at a concentration of 50 nM.