– Serpin E2 is a member of the Serpin superfamily. It is differentially expressed during neuronal differentiation and is able to transform human embryonic kidney cells into neuronlike cells. Its over-expression in mice leads to progressive neuronal and motor dysfunction in these animals. It is also over-expressed in the majority of pancreatic carcinoma as well as gastric and colorectal cancer samples whereas it is weakly expressed in all normal pancreas and chronic pancreatitis tissue samples. Serpin E2 is a potent inhibitor of thrombin, trypsin, urokinase, plasmin and plasminogen activators. It plays an important role in controlling male fertility because its knockout male mice show a marked impairment in fertility from the onset of sexual maturity and its abnormal expression is found in the semen of men with seminal dysfunction.