The present invention relates to a novel member of the plasminogen activator inhibitor protein family. In particular, isolated nucleic acid molecules are provided encoding the pancreas-derived plasminogen activator inhibitor protein. Pancreas-derived plasminogen activator inhibitor polypeptides are also provided as are vectors, host cells and recombinant methods for producing the same. The invention further relates to methods for treating physiologic and pathologic disease conditions, including breast cancer, and diagnostic methods for detecting pathologic disorders.