ESR1 and breast cancer: Hexachlorobenzene (HCB) is an organochlorine compound, which is able to bioaccumulate in high-fat tissues, that binds to the aryl hydrocarbon receptor, activating the membrane and nuclear pathways involved in BC development, such as ERα signaling, and insulin-like growth factor-1, epidermal growth factor, and transforming growth factor beta 1 receptors [326].