Retinoic acid (RA) concentrations and mRNA levels of retinoid responsive genes in the LRAT-deficient intestine and liver. Lrat−/− mice (n = 4–5 animals per dietary intervention group) were subjected to feeding with either vitamin A-deficient (VAD) diet, vitamin A-sufficient (VAS) diet, and β-carotene (BC) diet for 4 weeks. A: Intestinal RA concentrations in different dietary groups. B–E: Quantitative RT-PCR analysis for Isx, Bco1, Scarb1, and Cd36 mRNA levels was performed with total RNA preparation of the jejunum of different groups. B: Isx mRNA levels. (BC-supplemented mice were not significant for one-way ANOVA test). The red ∗∗∗ represent the statistical analysis for Student's t-test analysis. C: Bco1 mRNA levels. D: Scarb1 mRNA levels. E: Cd36 mRNA levels. β-actin was used as internal control. Data were normalized to the mRNA levels of Lrat−/− mice on VAD diet. F: Hepatic RA concentrations in different dietary groups. G–J: Quantitative RT-PCR analysis for Cyp26a1, Rarb, Aldh1a1, and Bco1 mRNA levels was performed with total RNA preparation of the livers of different groups. G: Cyp26a1 mRNA levels. H: Rarb mRNA levels. I: Aldh1a1 mRNA levels. J: Bco1 mRNA levels. β-actin was used as internal control. Data were normalized to the mRNA levels of Lrat−/− mice of the VAD group and are displayed as means ± SD. ∗P < 0.05, ∗∗P < 0.005, and ∗∗∗P < 0.0001. The statistical analysis was performed using one-way ANOVA by comparing VAD-fed mice as control. nd, not detectable; ns, not significant.