AZIN2 (antizyme inhibitor 2) is a polyamine metabolism regulator that functions as an enzymatically inactive ornithine decarboxylase (ODC) homolog. Its primary function is to counteract antizymes (OAZ1-3) by competing for antizyme binding, thereby preventing ODC degradation and restoring catalytically active ODC homodimers 1. This mechanism sustains polyamine biosynthesis essential for cellular homeostasis. Mechanistically, AZIN2 localizes to the trans-Golgi network (TGN) and endoplasmic reticulum-Golgi compartments 23. It regulates intracellular vesicle trafficking by locally activating polyamine synthesis; AZIN2 knockdown causes TGN fragmentation and impaired protein secretion, defects reversible by polyamine supplementation 2. Unlike ODC, AZIN2 exists as a labile monomer stabilized by antizyme binding and degraded through both proteasomal and lysosomal pathways 43. Clinically, AZIN2 dysregulation associates with multiple pathologies. Adipose-specific AZIN2 deficiency impairs progenitor maintenance, accelerating obesity, inflammation, and insulin resistance 5. In neurodegeneration, sustained AZIN2 overexpression exacerbates tau pathology and cognitive/behavioral deficits through altered polyamine acetylation 6. Conversely, cardiac AZIN2 splice variant knockdown improves post-infarction recovery by enhancing cardiomyocyte proliferation via PTEN/Akt pathway modulation 7. AZIN2 expression is particularly high in secretory tissues including brain, testis, and specialized epithelial cells 8.