Integrin beta7 is a 130 kD glycoprotein, also known as integin betap. It is a member of the Ig superfamily. In association with integrin alpha4 or alphaE chain, beta7 forms alpha4/beta7 or alphaE/beta7 heterodimer. alpha4/beta7 (CD49d/beta7, LPAM-1) is expressed on majority of peripheral lymphocytes, small subsets of thymocytes and bone marrow progenitors. LPAM-1 binds to several ligands, VCAM-1, MAdCAM-1 and fibronectin, and is involved in lymphocyte adhesion, some hematopoietic progenitor cells migration. alphaE/beta7 (CD103/beta7,alphaIEL/beta7) is expressed on intestinal intraepithelial lymphocytes (IEL), dendritic epidermal T cells, T regulatory cells, a subset of CD8+ T cells in lymph nodes and lamina propria. CD103/beta7 complex is thought to play a role in lymphocyte retention via interaction with its lignd E-Cadherin. The FIB27 antibody has been reported to react with mouse and human beta7 integrin and to block beta7 integrin-mediated cell adhesion in in vitro and in vivo studies.