The recruitment of lymphocytes from the circulation to the gut mucosa plays a critical role in inflammatory bowel disease (IBD); in particular, most classes of T cells promote disease; however regulatory T cells (Treg) suppress immune responses and resulting IBD. Integrin a4b7 is the most important cell adhesion molecule that mediates lymphocyte trafficking to gut-associated lymphoid tissues (GALT) and we previously showed that inside out integrin activation plays a pivotal role in this process.