Identification of the plasminogen activator(s) produced by the transformed liver cell line, SK-HEP-1

The availability of a cell line derived from an adenocarcinoma of the liver has made it possible to study the plasminogen activator(s) (PA) biosynthesized in culture by liver cells. Conditioned cultured media purified on fibrin-celite, benzamidine-Sepharose and immunoabsorbent anti-urokinase columns have shown the presence of multiple plasminogen activators when separated on sodium dodecyl sulfate polyacrylamide electrophoresis (SDS-PAGE). These PAs differ in molecular weight but all are urokinase-like based on their reaction with goat anti-urokinase and rabbit anti-tissue activator. Subcellular fractionation of the cultured cells shows the presence of activator in both the cytoplasmic and membrane fractions, but the higher molecular weight forms appear primarily in the cytoplasm.