Figure 4. Splenocytes from wild-type and AHR^d mice analyzed by qPCR for CYP1A1.

Spleens from these mice were harvested and suspended in culture media, and exposed to titrating doses of A) TCDD B) SU5416. After 4 hours they were analyzed by qPCR for CYP1A1 analysis. The curves are normalized from 0 to 100% response. Each graph is representative of 3 independent experiments. C–D. Cells transfected with AHR containing a valine point-mutation show similar ED₅₀ to Cos-1 cells with AHR^b isoform. Cos-1 cells were transfected with an AHR containing the same point mutation (valine for alanine) thought to be responsible for the low affinity of the AHR^d isoform compared to AHR^b, and compared to the wild-type AHR response. These cells also harbor a luciferase gene next to the DRE. C. Cos-1 cells were exposed to TCDD. D. Cos-1 cells were exposed to SU5416. The graphs represent normalized data from 0 response to 100% response. They are representative of 2 independent experiments.