AHR and neoplasm: For example, a study demonstrated that IFN-γ induced tumor-repopulating cells (TRCs) to enter dormancy to evade immunotherapy, which was mediated by an indolamine 2,3-dioxygenase 1 (IDO1)-kynurenine (Kyn)-aryl hydrocarbon receptor (AhR)-p27 dependent pathway [7].