Serpin F1 is secreted Neurotrophic protein and belongs to the serpin family. Serpin F1 Highly expressed in the liver, gastric glandular mucosa and renal tubules. It is also expressed in the brain, heart, lung retina and testes. It induces extensive neuronal differentiation in retinoblastoma cells. It is potent inhibitor of angiogenesis. As it does not undergo the S (stressed) to R (relaxed) conformational transition characteristic of active serpins, exhibits no serine protease inhibitory activity.