CCR4 and inflammatory bowel disease: Additionally, induction of stable expression of site-specific homing and chemokine receptors in Treg can confer the ability to migrate to preferential sites of chronic inflammation, for example, CCR4 for migration to the lung airways during allergic inflammation, CXCR4 for migration to the bone marrow, and CCR4/CCR9/CD62L/α4β7/αE(CD103)β7 for migration to the intestinal mucosa of IBD patients.