Summary
We have studied the expression of plasminogen activator inhibitor 2 (PAI-2) in the
adult mouse and during embryonic development using immunohistochemistry and the polymerase-chain
reaction. Mouse PAI-2 mRNA was mainly expressed in the skin, bone-marrow, spleen,
lung, thymus, and urinary bladder. Immunohistochemical studies suggested that PAI-2
was synthesized in macrophages and epithelial cells such as skin epithelial cells,
transitional cells of the urinary bladder, and mesothelial cell of peritoneum and
pleura. PAI-2 mRNA and antigen expression was observed only in the skin of 15 day-old
mouse embryos. These data suggest that PAI-2 may play a role in protecting the mouse
embryo from the protease attack in the amniotic fluid and also in maintaining and/or
protecting the structure of various surfaces in the mouse.