Role of plasminogen receptors (Plg-Rs) during monocyte/macrophage recruitment. Monocyte activation leads to expression of cytosolic pools of Plg-Rs at the cell surface. Plasminogen (Plg) binds to the Plg-R and is converted to plasmin (Plm) by Plg activators (uPA/tPA). The bound Plm facilitates transmigration and basement membrane degradation. As monocytes differentiate into macrophages, additional Plg-Rs support additional Plg binding, which aids in ECM degradation and macrophage recruitment. Enolase-1 functions as a Plg-R for monocyte recruitment into lung tissue.