Retinoid concentrations and Rarβ mRNA expression in white adipose tissue of wild type and Car −/− mice after PCB153 administration. Panels A and B – Retinyl ester (RE) and retinol (ROH) concentrations determined by HPLC in wild type and Car −/− adipose tissues of mice after administration of PCB153 (50 mg/kg body weight weekly for 4 weeks), either with or without oral retinyl acetate (Rac, 300 IU daily for 4 weeks) administration; Panel C – all- trans -Retinoic acid (atRA) concentrations were determined by UPLC/MS/MS in wild type and Car −/− adipose tissues of mice after administration of PCB153 (50 mg/kg body weight weekly for 4 weeks); Panel D – Gene expression values (normalized to 18S rRNA levels) were determined by qRT-PCR for RNA obtained from adipose tissues of mice after administration of PCB153 (50 mg/kg body weight weekly for 4 weeks), either with or without oral retinyl acetate (Rac, 300 IU daily for 4 weeks) administration. Values marked with different letters (a, b, c, d) are statistically different, P