1) Dactinomycin 
<drug, oncology> A relatively toxic antibiotic produced by the funguslike bacterium Streptomyces parvallum. ... It inhibits RNA transcription in eukaryotes and has antitumour properties, so it is often used in conjunction with other drugs in chemotherapy. ... (06 May 1997) ... 
Antibiotic from Streptomyces spp. that by binding to DNA blocks the movement of RNA polymerase and prevents RNA synthesis in both pro- and eukaryotes.
Type: Term Synonyms: dactinomycin
dactinomycin.