Fig. 4.

The overexpressed AHR protein predominantly localizes in the cytosol, rather than the nucleus. a Representative images and quantitative data illustrate the induction of CYP1A1 and CYP1B1 after B(a)P (10 μM) treatment. In H1299-AHR, neither CYP1A1 nor CYP1B1 is induced. b Immunofluorescent staining shows the overexpressed AHR protein located mainly in the cytoplasm. In the absence of B(a)P treatment, no AHR nuclear translocation occurs. c The distribution of AHR was determined using nuclear fractionation. Quantitative data are presented in Supplementary Fig. 5. B(a)P treatment causes a pronounced AHR N/C ratio, in comparison with non-treated groups. d The transactivation of XRE reporter is detected in B(a)P-treated groups (H1299-wt and H1299-AHR). In the absence of B(a)P stimulation, the overexpressed AHR protein alone did not induce XRE reporter activities. **p < 0.01 and ***p < 0.001 indicate a statistically significant difference from H1299-wt; ##p < 0.01 indicates a statistically significant difference from H1299-wt treated with B(a)P