Serpin A5, also known as PCI (Protein C Inhibitor) or PAI3 (plasminogen activator inhibitor 3), is a member of the serpin serine proteinase inhibitor family. This protein inhibits plasminogen activators as well as activated protein C. Serpin A5 is secreted in plasma, but is also expressed in liver. Serpin A5 is involved in cell inflammation, proliferation, apoptosis, tumour cell migration, invasion, and metastasis. Recombinant Serpin A5 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.