The extracellular matrix is a soluble and solid-phase agonist and receptor.

The components of the extracellular space have well-recognized structural functions. The role of the matrix as a conduit and/or repository for signals, however, has received much less attention. Because we know that cells require contact with the extracellular matrix for their normal function, that intact matrix and/or fragments of matrix in either soluble or solid phase can effect significant changes in cellular physiology, and that matrix components can be integral membrane proteins, we conclude that a major function of the matrix is as a soluble and solid-phase agonist and receptor.