An antibiotic Isolated from Streptomyces parvulus. A Potent, selective and competitive cell permeable rasfarnesyltransferase (FTase) inhibitor (IC₅₀ = 30 nM). Does not affect geranylgeranyltransferase (GGTase) (IC₅₀ = 180 µM). Blocks insulin-induced MAP kinase activation in rat cardiac myocytes (19 µM).µM). Inhibition is competitive with respect to farnesyl pyrophosphate and non-competitive with respect to Ras.