a The mRNA expression of AhR in NRK-52E cells transfected with CTL shRNA or AhR shRNA. b The mRNA expression of CYP1A1, CYP1A2, CYP1B1 and COX-2 in MP-induced NRK-52E cells treated with AhR shRNA. c The mRNA expression of AhR in RAW 264.7 cells transfected with CTL shRNA or AhR shRNA. d The mRNA expression of CYP1A1, CYP1A2, CYP1B1 and COX-2 in MP-induced RAW 264.7 cells treated with AhR shRNA. e The mRNA expression of AhR in NRK-49F cells transfected with CTL shRNA or AhR shRNA. f The mRNA expression of CYP1A1, CYP1A2, CYP1B1 and COX-2 in MP-induced NRK-49F cells treated with AhR shRNA. **P < 0.01 vs the CTL, scramble shRNA or scramble group; ##P < 0.01 vs the scramble group treated with MP.