Lactoferrin is a natural inhibitor of plasminogen activation.

The plasminogen system is essential for dissolution of fibrin clots, and in addition, it is involved in a wide variety of other physiological processes, including proteolytic activation of growth factors, cell migration, and removal of protein aggregates. On the other hand, uncontrolled plasminogen activation contributes to many pathological processes ( tumor cells' invasion in cancer progression). Moreover, some virulent bacterial species ( or ) bind human plasminogen and hijack the host's plasminogen system to penetrate tissue barriers.