OAT and cancer: Diazonamide is a new class of marine natural products that show remarkable activity in inhibiting cancer cell growth when tested in a panel of 60 NIH cell lines.5 The pattern of the inhibition mirrors other tubulin destabilizing agents.6,7 Diazonamide itself is not a good tubulin binder and its precise mechanism of action remains to be determined although it has been shown to bind to ornithine amino transferase (OAT) with high affinity.8 The relevance of OAT and other diazonamide-interacting proteins to its antimitotic function remains unclear.