Figure 1. .

Characterization of test compounds in SPA-based RBP4 binding experiments. (A) Saturation isotherm for the binding of ³H-retinol to human RBP4. Biotinylated RBP4 (50 nM) was incubated with increasing concentrations of ³H-retinol (0.37–270 nM) in a total volume of 100 μL. Nonspecific binding was assessed in the presence of 20 μM nonradioactive retinol. Presented results are from the representative experiment performed in triplicate. Similar titration data were obtained in two additional experiments. (B) Representative isotherms of A1120 and fenretinide binding to human RBP4. ³H-retinol at 10 nM was used as a radioligand. Upper inset shows the A1120 structure.