Increased activation of AHR in IVC of animals with colon cancer xenografts. (A) Experimental design. A group of 8- to 10-week-old (total 8 mice, 4 mice of each sex) athymic mice were injected with HT-29 cells. Mice without HT-29 with the same sex distribution served as controls. At the end of 4 weeks, the xenograft volumes in these mice were 418.19 ± 26.93 mm³ (in the same range as those in Figure 1B). No IVC ligation was performed in these groups. (B) AHR status in the IVC of mice with colon cancer xenografts. IVCs harvested from control (CTL) and colon cancer xenograft-bearing mice (HT-29) were stained with prevalidated anti-AHR¹⁶  and anti-CD31 antibodies and imaged by using confocal microscopy. Alexa Fluor secondary antibodies were used. 4′,6-Diamidino-2-phenylindole (DAPI) was used for nuclear stain. Representative images from a segment IVC of 8 animals analyzed per group are shown. The inserts show a representative endothelial cell with AHR in cytosol and in the nucleus. Scale bar = 10 μm. (C) The IVC of xenograft-bearing mice contained a higher percentage of endothelial cells with nuclear AHR. Each group consisted of 8 IVCs from a total of 8 mice in each experimental group: males (n = 4) and females (n = 4). One section of IVC was examined per mouse. Three high-power field images, randomly obtained, were analyzed by using a laser confocal microscope. In essence, 24 images per group were examined and presented as percentage of endothelial cells positive for nuclear AHR. **P = .025.