CYP1A1 and inflammatory bowel disease: Figure 6 proposes a possible explanation of the link between the AhR pathway and IBD. PAHs such as benzo(a)pyrene, are bioactivated by CYP1 family enzymes into diolepoxides, such as benzo(a)pyrene diol epoxide [20], which activate NFκB [16]. The activation of NFκB promotes an inflammatory loop via IL-1β expression and induces AhR expression.