Integrins are cell-surface proteins with important roles in cell adhesion, migration and cell surface mediated signalling. The integrin family contains at least 18 alpha and 8 beta subunits that form alpha/beta heterodimers. The integrin alpha-4 subunit is also known as CD49D. It associates with either beta-1 or beta-7 subunits to form receptors for fibronectin and VCAM1.