Integrin alpha 11 beta 1 is a noncovalent heterodimeric collagen receptor that contains a 150 kDa alpha 11 subunit complexed to a 130 kDa beta 1/CD29 subunit.  alpha 11 beta 1 is the only known alpha 11-containing integrin. By contrast, at least twelve alpha -integrins share the beta 1 subunit (1-5). alpha 11 beta 1 is expressed on fibroblasts from cornea, skin and periodontal ligament (3-9). It is also expressed on mesenchymal stem cells and is considered a marker for non-muscle mesenchymal tissue (3, 8-10). Expression of alpha 11 beta 1 is stimulated by TGF-beta 1, activin A, and type I interferons, and down‑regulated by FGF-2 (6, 9-11). The alpha 11 extracellular domain (ECD) contains a vWFA domain which includes the ligand binding site (2-5). The beta 1 ECD also contains a vWFA domain, which participates in binding. Each subunit has a transmembrane sequence and a short cytoplasmic tail. The dimer assumes a folded configuration at "rest". Divalent cations and intracellular (inside-out) signaling convert it to an active, extended and open conformation (1, 2). The 1119 amino acid (aa) mouse alpha 11 ECD shares 90% and 95% aa sequence identity with rat and human alpha 11, respectively, while the 708 aa mouse beta 1 ECD shares 98% aa identity with rat and 93-94% aa identity with human, bovine, porcine, ovine, canine and feline beta 1. I domain-containing beta 1 integrins alpha 1 beta 1, alpha 2 beta 1, alpha 10 beta 1 and alpha 11 beta 1 all bind collagens (3-5). alpha 11 beta 1 preferentially binds interstitial collagens such as type I (5, 8, 12). It can contract collagen matrices and influence inflammatory edema (3, 13). Depending on context, alpha 11 beta 1 can support or inhibit cell migration on collagen (7, 8). It is frequently up‑regulated in the stroma of lung adenocarcinomas and enhances tumorigenicity (14, 15). alpha 11 beta 1 is also involved in myofibroblast differentiation in human corneal fibroblasts and human cardiac fibroblasts (9, 16).