Urokinase plasminogen activator surface receptor (U-PAR) is also known as PLAUR, Monocyte activation antigen Mo3, CD antigen CD87. PLAUR contains three UPAR/Ly6 domains. U-PAR is expressed in neurons of the rolandic area of the brain (at protein level) and is also expressed in the brain. PLAUR / CD87 interacts with MRC2, SRPX2 and SORL1. PLAUR / UPAR acts as a receptor for urokinase plasminogen activator and plays a role in localizing and promoting plasmin formation. U-PAR mediates the proteolysis-independent signal transduction activation effects of U-PA.