ABCB1 and inflammatory bowel disease: Interestingly, a subset of intestinal human memory CCR6+CXCR3+ T cells co-expressing Th17 and Th1 markers from CD patients express the Multidrug Resistant Mutation MDR1, a plasma membrane drug efflux pump (125) that is encoded in a gene strongly associated with IBD (ABCB1) (126).