MAdCAM-1 is an immunoglobulin (Ig) cell adhesion molecule family member. MAdCAM-1 is involved in lymphocyte homing to mucosal sites and is expressed on high endothelial venules (HEV) of both mesenteric lymph nodes and Peyer's patches. It has also been found to be expressed on sinus-lining cells of the spleen. The integrin, alpha 4 beta 7, has been shown to function as the MAdCAM-1 receptor. The Ig domains of MAdCAM-1 have been found to be critical to alpha 4 beta 7 binding. The mucin domain has been shown to have activity in L-Selectin binding.