AHR and neoplasm: The cg05575921 site is in an enhancer-like regulatory element within AHRR, which is a putative tumor suppressor gene whose expression downregulates the aryl hydrocarbon receptor (AHR); it is involved in pro-inflammatory signaling in human circulating monocytes [21,22] and is a critical regulator for metabolizing carcinogens from tobacco smoke, such as dioxin toxicity [23].