Extracellular matrix protein that seems to be a ligand for ITGA8:ITGB1, ITGAV:ITGB1 and ITGA4:ITGB1 (By similarity) (PubMed:17909022). Involved in neurite outgrowth and cell migration in hippocampal explants (By similarity). During endochondral bone formation, inhibits proliferation and differentiation of proteoblasts mediated by canonical WNT signaling (By similarity). In tumors, stimulates angiogenesis by elongation, migration and sprouting of endothelial cells (PubMed:19884327). Expressed in most mammary tumors, may facilitate tumorigenesis by supporting the migratory behavior of breast cancer cells (PubMed:17909022). Homohexamer. Not detected in normal adult mammary tissues or brain but expressed in most breast tumors and brain tumors, such as glioblastomas, astrocytomas and oligodendrogliomas, tested (PubMed:17909022, PubMed:19884327). In brain tumors, detected around the endothelial cell layer of the clood vessels (PubMed:19884327). Belongs to the tenascin family.