Phosphacan, previously designated 3F8 chondroitin sulfate proteoglycan or 3H1 keratan sulfate proteoglycan depending on the glycosylation status, is a soluble nervous tissue-specific proteoglycan. It is synthesized by glia and binds to neurons and to the neural cell adhesion molecules tenascin, N-CAM or NG-CAM but not to laminin and fibronectin. Phosphacan acts as a potent inhibitor of cell adhesion and neurite outgrowth.