Heparanase is an endo-beta-D-glucuronidase, which degrades heparan sulfate side chains of heparan sulfate proteoglycans (HSPGs) in the extracellular matrix. Heparanase plays an important role in ECM degradation, facilitating the migration and extravasations of tumor cells and inflammatory leukocytes. Upon degradation, heparanase releases growth factors and cytokines that stimulate cell proliferation and chemotaxis. Heparanase is a heterodimer comprised of a 50 kDa subunit harboring the active site and an 8 kDa subunit. It is produced as a latent 65 kDa precursor and proteolytically processed to its active form. Heparanase is highly expressed in myeloid leukocytes (i.e. neutrophils) in platelets and in human placenta. Human heparanase was found to be upregulated in various types of primary tumors, correlating in some cases with increased tumor invasiveness and vascularity and with poor prospective survival.