Serum retinyl esters (RE) (A and B), retinol (ROL) (C and D), RBP4 (E and F), and atRA (G and H) concentrations in Cyp26a1−/− mice compared with Cyp26a1+/− and Cyp26a1+/+ (control) mice. The notation Adult indicates that tamoxifen injections were done in 2-month old mice, and Juvenile indicates the mice in which tamoxifen injections were done at 21 days of age. In all panels, the horizontal lines indicate mean values, and error bars indicate S.D. Each data point represents an individual mouse. Significant differences were analyzed by two-way ANOVA; ***, p < 0.001; €, p < 0.05, €€€, p < 0.001.