CCL25 and ulcerative colitis: However, given the lack of safe, orally administered treatments for ulcerative colitis, the increase in colonic CCL25 levels (Figure 3) and circulating CCR9+ leukocytes [17, 20] during disease, and the remarkable activities of CCR9 antagonists in the mdr1a−/− model of ulcerative colitis (Figures 4 and 5), exploring CCR9 antagonism as a therapy for ulcerative colitis seems appropriate.