The aryl hydrocarbon receptor (AhR) is a protein found in cells that functions as a receptor for various environmental toxins and pollutants, including certain types of aromatic hydrocarbons. When activated by these substances, the AhR plays a role in regulating gene expression and controlling cellular responses, including detoxification pathways. It is involved in processes such as xenobiotic metabolism, immune responses, and development. Additionally, the AhR has been linked to various health effects and disease conditions, including cancer, immune disorders, and reproductive abnormalities. Overall, the AhR serves as a molecular sensor that interacts with environmental chemicals and influences cellular and physiological responses.