Geninthiocin is a thiopeptide antibiotic isolated from a Streptomyces sp. Geninthiocin displays a 10-fold selectivity for bacteria over mammalian cells lines, whereas the related dedialanyl geninthiocin shows the reverse selectivity. Geninthiocin is closely related to siomycin, a recently discovered inhibitor of oncogenic transcription factor, FoxM1.