The chemokines CXCL1 and CXCL2 and their receptor CXCR2 play an important role in experimental colitis because the deletion of CXCR2 alleviates chronic colitis and associated tumors by inhibiting the penetration of myeloid derived suppressor cells (MDSCs) into the colon mucosa. The gene discussed is CXCR2; the disease is colitis.