The heparan sulfate chains of perlecan bind growth factors in the ECM, and serve as co-ligands or ligand enhancers when bound to receptors. Another study showed that release of HS-bound basic FGF in culture could be achieved through treatment with stromelysin, heparitinase I, rat collagenase and plasmin, and these proteolysis sites are illustrated in figure 1. This was proposed as a non-exhaustive list of the proteases that could mediate release of growth factors from the heparan sulfate chains of perlecan. Although Whitelock et al. suggested that thrombin cleavage consensus sequences exist in the core protein of perlecan, they also postulate that any thrombin activation of perlecan actually comes from cleavage of other ECM constituents. This article states that heparanase is responsible for cleavage of the heparan sulfate chains of perlecan in matrix. This releases growth factors bound to the heparan sulfate, specifically FGF-10. Addition of heparanase to cell culture of epithelia in basement membrane caused an increase in epithelial cell proliferation due to FGF-10 release.