Plasminogen Activator, Urokinase Receptor (uPAR) is the receptor for urokinase plasminogen activator and, given its role in localizing and promoting plasmin formation, likely influences many normal and pathological processes related to cell-surface plasminogen activation and localized degradation of the extracellular matrix. The urokinase receptor (uPAR) was identified as the membrane receptor of the serine protease urokinase (uPA), thereby implicated in the plasminogen activation cascade and regulation of pericellular proteolysis, thus a binding ELISA assay was conducted to detect the interaction of recombinant mouse uPAR and recombinant human uPA. Briefly, uPAR was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100μl were then transferred to uPA-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-uPAR pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50μL stop solution to the wells and read at 450/630nm immediately. The binding activity of recombinant mouse uPAR and recombinant human uPA was shown in Figure 1, the EC50?for this effect is 0.069 ug/mL.