cellular detoxification pathway aryl hydrocarbon receptor signaling pathway AhR signaling pathway Aryl hydrocarbon receptor signalling PW:0000370 The aryl hydrocarbon receptor (AhR) is a transcription factor whose ligands include a variety of aromatic hydrocarbons and which regulates the expression of phase I and phase II drug- and xenobiotic-metabolizing enzymes. Phase I enzymes convert otherwise inactive hydrocarbons into active metabolites with potential carcinogenic effects, thus rendering AhR a player in tumor initiation. pathway xenobiotic metabolic pathway basic helix-loop-helix signaling pathway