The extracellular matrix, otherwise known as the ECM, contains the proteins fibronectin, collagen and elastin. The ECM regulates intercellular communication.
Each of the various protein fibers within the ECM serves a different purpose. Collagen constitutes about 30 percent of the total protein mass of a multicellular animal, making it the most numerous protein fiber in the ECM. Collagen gives the body its ability to stretch. In more academic terms, collagens regulate cell adhesion, support chemotaxis and provide tensile strength and direct tissue development.
Elastin is also a prevalent protein that works with collagen. Elastin is what allows the lungs and other parts of the body to stretch and move. Specifically, elastin allows those parts of the body to return to their former shape after being stretched. Collagen and elastin work together in this regard, with collagen serving to limit the degree to which an organ or part of the body can stretch, and elastin bringing it back to its original shape.
Fibronectin's function is to direct the organization of the ECM itself. Fibronectin also serves as a mediator of cell attachment and function. Fibronectin provides crucial services to the body during cell migration during development. Some suggest that fibronectin has an impact on causing cardiovascular disease and tumor metastasis in cases where it malfunctions.