Fibronectin is a multi-domain glycoprotein, found in a soluble form in plasma, and in an insoluble form in loose connective tissue and basement membranes, that binds cell surfaces and various compounds including collagen, fibrin, heparin, DNA, and actin.

Fibronectins are involved in a number of important functions e.g., wound healing; cell adhesion; blood coagulation; cell differentiation and migration; maintenance of the cellular cytoskeleton; and tumour metastasis.

[3] Type II domain is approximately sixty amino acids long,[4] contains four conserved cysteines involved in disulfide bonds and is part of the collagen-binding region of fibronectin.

[11] Fibronectin type II domain is part of the extracellular portions of EphA2 receptor proteins.

[12] K441 and R443 together make up a membrane-binding motif that allows EphA2 receptors to attach to the cell membrane.