Anti-PAI antibodies enable researchers to detect and measure the PAI antigen in biological samples. This target is a reported synonym of the SERPINE1 gene, which encodes serpin family E member 1. This protein is known to function in angiogenesis and the cellular response to lipopolysaccharides, among other biological roles. The human version of PAI has a canonical amino acid length of 402 residues and a protein mass of 45.1 kilodaltons, although 2 isoforms have been identified. It is reported to be a secreted protein. PAI is a member of the Serpin protein family.