Figure 4. The retinol-binding protein 4 (RBP4)/transthyretin (TTR) molar ratio is extremely high in neuronal retina tissue. A: TTR levels in perfused retinal neuronal tissue lysates from wild-type and RBP4-Tg mice were measured by enzyme-linked immunosorbent assay (ELISA). B: RBP4/TTR molar ratio in mouse serum versus retina. RBP4-Tg and WT mice aged 10 weeks (serum samples) and 6 months (retinal lysate) was used to measure RBP4 and TTR levels by ELISA. Values are mean ± standard deviation (SD); n≥5 mice per genotype. Student’s t-test confirms that the means in panel B have a statistical difference between wild-type and RBP4-Tg of p< 0.01 for the retina, and p <0.001 for serum.