ABSTRACT
Fibronectin is a high-molecular-weight protein present as a soluble molecule in plasma and as fibrils on the surface of adherent cells (for recent reviews see Refs. 1 to 4). It expresses affinity to various extracellular substrates, including collagen, heparin, and fibrin. In addition, it has a binding site for cell surface receptors [5] and thus is capable of mediating various interactions of cells with those compounds. It is important for attachment and spreading of cells on various extracellular structures and is involved in the locomotion of the cells along those substrates. Fibronectin is also necessary for binding of bacteria, effete proteins, and cellular waste products by cells of the reticuloendothelial system and thus becomes an essential factor of the defense and blood clearing system [6,7].
