Figure 1. Cartoon of perlecan domain structure with 3 glycosaminoglycan chains, typically heparan sulfate, covalently attached to domain I of the protein core. Various homologies and purported functions are ascribed to each domain. SMC, smooth-muscle cell; EC, endothelial cell; FGF, fibroblast growth factor; MMP, matrix metalloproteinase; EGF, epithelial growth factor; LDL, low-density lipoprotein; ECM, extracellular matrix.