AHR and neoplasm: The proposed biological implications of these gene expression changes are also conflicting, with some studies suggesting that the inhibition of the AhR pathway may compromise the body’s capacity to metabolize harmful environmental chemicals among those exposed to smoke [3], whereas others suggest that the feedback response of AHRR in relation to smoke exposure is actually adaptive because it inhibits the released of carcinogenic metabolites produced by the AhR pathway [40], which is in part corroborated by the role of AHRR as a putative tumor suppressor [41].