The tenascin family of extracellular matrix proteins includes Tenascin-C (also designated cytotactin or Tenascin), Tenascin-R (also designated restrictin, TN-R or janusin) and Tenascin-X. Tenascin proteins function as substrate-adhesion molecules (SAMs) and are involved in regulating numerous developmental processes, such as morphogenetic cell migration and organogenesis. The tenascin family proteins arise from various splicing events in the region of coding for FNIII repeats. Tenascin-C and Tenascin-X are expressed in several tissues during embryogenesis and in adult tissues undergoing active remodeling, such as healing wounds and tumors. Tenascin-R is expressed on the surface of neurons and glial cells.