Identification of an adhesion factor for chondrocytes.

The attachment of chondrocytes to collagen substrates is stimulated by serum but not by fibronectin. The active material in serum was partially purified and was shown to be a protein by its sensitivity to trypsin and heat and its chromatographic properties. This factor, which we have named chondronectin, is distinct from fibronectin and does not stimulate fibroblast attachment. Because material with similar attachment-enhancing activity is produced by chondrocytes and is extractable from cartilage, chondronectin may be a chondrocyte-specific attachment protein.