Versican is a large extracellular matrix proteoglycan that is present in a variety of tissues. Successful cloning of the gene in man, mouse, cow and chicken has revealed the existence of at least four splice variants of versican, which differ in the size of the core protein and the number of glycosaminoglycan chains. The highly interactive nature of versican provides a basis for its importance as a structural molecule, creating loose and hydrated matrices during key events in development and disease; and by interacting either directly with cells or indirectly with molecules that associate with cells to, in part, regulate cell adhesion and survival, cell proliferation, cell migration and extracellular matrix assembly. Several studies within the past two years have confirmed a significant role for versican in regulating cell phenotype.