Antizymes (AZs) are polyamine-induced proteins that promote degradation of ornithine decarboxylase (ODC), the key enzyme in the polyamine biosynthetic pathway []. AZs also negatively regulate polyamine transport into the cells through an unknown mechanism []. AZs are in turn regulated by antizyme inhibitors (AZIN1 and AZIN2), which are proteins homologous to ODC that bind to AZs and counteract their negative effect on ODC [].AZIN1 is expressed in most tissues of mouse and participates in polyamine metabolism and cell growth []. AZIN1 is induced by various proliferative stimuli and repressed by polyamines, forming a negative feedback loop [].
