CYP1A protein and mRNA expression in OPAH exposed zebrafish embryos: Panels A–F show CYP1A expression at 120 hpf in wildtype and AHR2-null embryos exposed from 6 to 120 hpf. CYP1A immunohistochemistry of wildtype embryos exposed to 1% DMSO (A), 20 μM BEZO (B), 20 μM XAN exposed to wildtype (C) or AHR1A morphant embryos (E), and 5 μM 7,12-B[a]AQ exposed to wildtype (D) or ahr2-null (ahr2hu3335) mutant embryos (F). qRT-PCR of cyp1a, cyp1b, cyp1c1, and cyp1c2 mRNA at 48 hpf (G) and 120 hpf (H).