A-E, MCF-7 cells were treated with DMSO or 10 nM TCDD for 45 minutes. Cells were then subjected to ChIP with non-specific IgG (IgG), or AHR, ARNT, p300, acetylated histone H3 (lysine 9 or 14) targeting antibodies, followed by qPCR amplification of the AHR binding site in the LAT1 (A-C) or CYP1B1 (D & E) genes. Significant increases in AHR, ARNT, or p300 binding to AHR binding sites in the LAT1 (A-C) or CYP1B1 (D & E) gene by TCDD are indicated by *, P < 0.05, or **, P < 0.01. C, Significant increases in the acetylation of lysine 9 or 14 in histone H3 at the AHR binding site in the LAT1 gene by TCDD are indicated by #, P < 0.05. Data shown are the means ± S.E. of three independent experiments.