In order to confirm the implication of AHR in the regulation of inflammation genes, we examined the effect of two AHR ligands: TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) and BaP (benzo[a]pyrene), on mRNA expression of several inflammation genes: IL1B, IL6, TNF, IL8 and CXCR4, in MDA-MB-436 ERα-negative breast cancer cells. The gene discussed is CXCR4; the disease is breast carcinoma.