Fibronectin type III domain B (EIIIB domain)

The **EIIIB domain of fibronectin** (also called **ED-B**, **FN-EDB**, or **type III B domain**) is an ~90 amino acid, alternatively spliced type III domain within the large extracellular matrix glycoprotein fibronectin. Under physiological conditions, EIIIB is minimally expressed in most adult tissues but is highly upregulated during embryogenesis, tissue remodeling, wound healing, and—critically—in pathological settings such as tumorigenesis, fibrosis, and chronic inflammation[1][5][6][7]. Functionally, the EIIIB domain is believed to modulate cell adhesion, migration, and proliferation, influencing how fibronectin binds cells (notably via integrins), other matrix components, and thereby promoting angiogenesis and tissue reorganization[4][7]. Structurally, the presence of EIIIB alters fibronectin conformation and cell-adhesion characteristics[1][4]. EIIIB-containing fibronectin isoforms have been extensively studied as selective markers and therapeutic targets in cancer and regenerative medicine due to their restricted and disease-associated expression profiles[6][7].

Other names

EIIIBED-Bextradomain BFN-EDBB domainEDB domaintype III B domain

Therapeutic strategies generally involve antibodies or peptides targeting EIIIB to deliver cytotoxic agents or imaging moieties to sites of neovascularization or tumors, rather than direct modulation of EIIIB function[7]