To determine the role of NR2E3 in AHR status and AHR–mediated responsiveness in vivo, we employed Nr2e3Rd7/Rd7 (retinal degeneration 7, Rd7) mutant mice (Jackson laboratory, Bar Harbor, MI) expressing non-detectable levels of Nr2e3 in the retina40, 41. Here, NR2E3 is linked to retinal degeneration.