OAT and neoplasm: Comparing the effects of inhibiting OAT and ornithine decarboxylase 1 (ODC1), the rate-limiting enzyme in polyamine synthesis, the authors found that OAT inhibition using 5-fluoromethylornithine (5-FMO) suppressed glutamine-derived ornithine and putrescine synthesis specifically in PDA cells, leading to reduced tumor-growth.