Isolated from Micromonospora rhodorangea. Antibiotic. Cytotoxic to prokaryotic and eukaryotic cells by inhibiting the protein synthesis. Apoptosis inducer. Widely employed in the selection of eukaryotic expression vectors, in combination with either aminoglycoside phosphotransferase 3' or APH II. Antiviral. Assay: >700 µg/mg. Biological Assay: ED50 Resistant: >2500 µg/ml. Biological Assay: ED50 Sensitivity: <400 µg/ml.