An anti-tumor antibiotic isolated from the bacterium Streptomyces pulveraceus. Fostriecin inhibits topoisomerase II catalytic activity, resulting in protein-associated strand breaks and impaired DNA and RNA synthesis in various malignant cell types. This agent also inhibits serine/threonine protein phosphatase type 2A in some tumor cell types, thereby interfering with cellular proliferation and differentiation. Check for active clinical trialsusing this agent.