The CCR9 receptor is a GPCR expressed selectively in the thymus, lymph node, spleen, and the small bowel (SB). CCR9 binds to Thymus-expressed chemokine ligand (TECK / CCL25), and is involved in directing the movement of mature T cells in the thymus. CCR9 also plays an important role in the pathogenesis of SB Crohn"s disease. The CCR9 selective expression in the small bowel but not the colon indicates the the role of CCR9 in the specialized immune response in the SB. It was also shown that CCR9-mediated antiapoptosis could help in the study of cell survival mechanism and T cell malfunctioning.