Heparan sulfate proteoglycans (HSPGs) are found on cell surfaces and in the extracelluar matrix of all mammalian tissues, particularly in the core of the basement membrane. HSPGs found in the brain are dystroglycan, N-syndecan, glypican, and perlecan. The composition of HSPGs differs in the protein core, and is thought to determine the location of HSPG in the cell membrane (syndecan and glypican) and extracellular matrix (perlecan and dystroglycan). The postulated functions of HSPG include cell proliferation, differentiation, adhesion, migration and morphogenesis.