From a mechanistic point of view in the biology of cancer and especially breast cancer, dl-PCB congeners target mainly the AhR, which has been demonstrated to cross-talk with ER signaling (Ohtake et al. 2011) and both might down-regulate breast tumor proliferation by this way and promote tumor escape by ER-negative phenotype expression (Feng et al. 2013). The gene discussed is ESR1; the disease is cancer.