AHR and neoplasm: Interestingly, many studies have also provided evidence for a tumor suppressor role for AhR, with evidence that AhR can inhibit tumor growth (Fritz et al., 2007; Jin et al., 2014; Feng et al., 2020) while inhibition of AhR or AhR deficiency promotes tumor development (Abdelrahim et al., 2003; Safe et al., 2017).