Several agrin (AGRN) ligands require the presence of heparan-sulfate sidechains and are probably mediated by them. Membrane-associated AGRN ligands include the neural cell adhesion molecule NCAM1 (Burg et al. 1995, Tsen et al. 1995, Cole & Halfter 1996 - represented in REACT_19071) and receptor protein tyrosine phosphatase sigma (PTPRS) (Aricescu et al. 2002).