OAZ1 (ornithine decarboxylase antizyme 1) is a negative regulator of polyamine metabolism that functions as a key checkpoint for intracellular polyamine homeostasis. Primary function: OAZ1 inhibits ornithine decarboxylase (ODC) activity by binding to ODC monomers, preventing homodimer assembly and targeting them for proteasome-mediated degradation 123. It also suppresses cellular polyamine uptake by inactivating polyamine transporters, providing dual-level metabolic control 4. Mechanism: OAZ1 triggers ODC degradation by exposing a cryptic proteasome-interacting surface 2, and its expression is regulated epigenetically through histone acetylation at its promoter 5. Disease relevance and clinical significance: OAZ1 dysregulation is implicated in multiple pathologies. The OAZ1+2222A/G polymorphism associates with coronary in-stent restenosis, carotid atherosclerosis, and coronary heart disease, linking polyamine metabolism to vascular disease 6. Downregulation of OAZ1 promotes cisplatin resistance in lung cancer, with HDAC inhibitor-mediated OAZ1 restoration overcoming chemotherapy resistance 5. Elevated OAZ1 expression appears in endometrial cancer development driven by metabolic syndrome 7. Conversely, OAZ1 upregulation correlates with fetal growth restriction risk 8. OAZ1 shows diagnostic potential as a salivary biomarker for oral squamous cell carcinoma detection 9. Finally, OAZ1 knockout enhances recombinant protein production in cell lines, suggesting biotechnological applications 10.