CYP1A1 and malignant colon neoplasm: IL-22 that has also been linked to colon cancer in mice and humans (Jiang et al., 2013, Kryczek et al., 2014) is elevated in VillinCreAhrfl/fl mice, probably due to increased levels of AHR ligands accessible to mucosal immune cells, as Ahr-deficient IECs do not express CYP1A1.