Inostamycin A is a bacterial metabolite that has been found inStreptomycesand has anticancer activity.1It is an inhibitor of CDP-diacylglycerol:inositol 3-phosphatidyltransferase (IC50= 0.02 ug/ml in A431 cell membranes) and is selective for CDP-diacylglycerol:inositol 3-phosphatidyltransferase over phospholipase C (PLC) and phosphatidylinositol kinase at 10 ug/ml.2Inostamycin A decreases viability of YCU-T892, KCC-TC873, KB, HSC-4, and YCU-T891 oral squamous cell carcinoma (OSCC) cells in a concentration-dependent manner.3It induces cell cycle arrest in the G1phase in HSC-4 cells when used at a concentration of 250 ng/ml and induces apoptosis in Ms-1 small cell lung cancer cells at 300 ng/ml.3,4Inostamycin A also reduces levels of matrix metalloproteinase-2 (MMP-2) and MMP-9 and inhibits EGF-induced migration of HSC-4 cells.5