VCAM-1 (CD106), a member of the immunoglobulin superfamily, is a cell surface protein expressed by activated endothelial cells and certain leukocytes (such as macrophages). VCAM-1 expression is induced by IL-1 beta, IL-4, TNF-alpha and IFN-gamma. VCAM-1 binds to leukocyte integrins VLA-4 and alpha 4 beta 7. The human and mouse VCAM-1 proteins share approximately 76% amino acid similarity.