Integrins are heterodimers composed of noncovalently associated transmembrane alpha and beta subunits, which heterodimerize to produce more than 20 different receptors. Most Integrin receptors bind ligands that are components of the extracellular matrix, including Fibronectin, collagen (COL) and Vitronectin. Certain Integrins can also bind to soluble ligands, such as Fibrinogen, or to counterreceptors on adjacent cells, such as the intracellular adhesion molecules (ICAMs), leading to cellular aggregation. Integrin ?1, also known as ITGA11 or MSTP018, is a 1,189 amino acid single-pass type I membrane protein that contains one VWFA domain and seven FG-GAP repeats. Expressed at high levels in heart and uterus and present at lower levels in pancreas, kidney, skeletal muscle, placenta, lung, colon and brain, Integrin alpha 11 exists as a heterodimer with Integrin beta1 and functions as a receptor for collagen.