CD87, known as urokinase plasminogen activator-receptor (uPAR), is a 36-68 kD single-chain glycophosphotidylinositol (GPI)-anchored glycoprotein. The extracellular region of CD87 consists of three homologous domains, D1, D2, and D3. Membrane-bound and soluble (D2D3) forms of uPAR have been reported. The membrane-bound CD87 is expressed on granulocytes, monocytes/macrophages, dendritic cells, fibroblasts, endothelial cells and keratinocytes. CD87 plays a role in cell adhesion and chemotaxis through binding to β1, β2 and β3 integrins. CD87-bound uPA converts plasminogen to plasmin.