THE CELLULAR AND MOLECULAR-BIOLOGY OF PLASMINOGEN-ACTIVATOR INHIBITORTYPE-2

PAI-2, the most enigmatic member of the serine protease inhibitor gene superfamily, is generally recognised as an inhibitor of urokinase (u- PA) and, to a lesser extent, tissue-type plasminogen activator. The ro le of plasminogen activator inhibitor type-2 (PAI-2) in the regulation of a u-PA-mediated proteolysis is well established. However, the pred ominantly cytosolic location of PAI-2 has raised much speculation as t o the role this serpin plays in intracellular proteolysis and in parti cular in the events leading to cellular differentiation and apoptosis. In vitro studies have highlighted the fact that PAI-2 is one of the m ost tumour necrosis factor (TNF) responsive genes so far described sug gesting that PAI-2 may also play a significant role in TNF biology.