Serpinb2, also known as plasminogen activator inhibitor type 2 (PAI-2), is widely described as an inhibitor of extracellular urokinase plasminogen activator. However, its real biological role remains largely unknown. High-throughput studies suggest its functions in inflammation, autoimmune disorders, and carcinogenesis modulation. It is acutely up-regulated by various stimuli, including aryl hydrocarbon receptor ligands [1].

In gene knockout mouse models, Serpinb2-/-mice have shown several phenotypes. In breast cancer, Serpinb2-deficient MMTV-PyMT mice had delayed tumor progression, reduced tumor cell dissemination, and altered macrophage polarization with decreased pro-tumorigenic M2 and increased M1 markers [2]. In kidney injury and aging, Serpinb2-knockout mice had enhanced kidney damage and fibrosis, along with changes in inflammatory cell infiltration, macrophage phagocytosis, and migration [3]. In hemostasis, Serpinb2-deficient mice had reduced bleeding times due to dysregulated platelet activation [4].

In conclusion, Serpinb2 plays important roles in multiple biological processes and diseases. Gene knockout mouse models have revealed its functions in tumor development, immune response in kidney injury and aging, and hemostasis. These findings contribute to understanding the role of Serpinb2 in specific disease areas, providing insights for further research and potential therapeutic strategies.