Syndecans have attached heparan sulfate (HS) and to a lesser extent chondroitin sulfate (CS) chains. These allow interactions with a large number of proteins, including heparin-binding growth factors such as fibroblast growth factors (Kiefer et al. 1990, Bernfield & Hooper 1991, Steinfeld et al. 1996), vascular endothelial growth factors (VEGFs) and transforming growth factor-Beta (Chen et al. 2000, Ishiguro et al. 2002). Various enzymes involved in post-translational HS chain modifications produce unique binding motifs that selectively recognize different proteins (Tkachenko et al. 2005). HS chains facilitate interactions of syndecan-1 with extracellular matrix proteins, including thrombospondin-1 (Sun et al. 1989, Lebakken & Rapraeger 1996, Adams et al. 2001, Yoneda & Couchman 2003). Syndecan-null mice have subtle phenotypes when compared with mice deficient in HS chain synthesis or modification (Echtermeyer et al. 2001, Ishiquro et al. 2001, Götte et al. 2002). GPI-anchored glypicans and matrix HSPGs such as perlecan may compensate for the absence of syndecans.