Figure 1. ARPCA binds and antagonizes FGF8b.

A. SPR analysis of ARPCA binding to immobilized FGF8b. B. Increasing concentrations of ARPCA and of peptide mutants were tested by SPR analysis for the capacity to bind the FGF8b sensor chip and the affinity of interaction (K_d, mean ± SEM) was calculated for each peptide. nb, no binding. A schematic representation of ARPCA peptide is shown on the right. C. Overlay of selected region of 2D ¹H-¹³C HSCQ NMR spectra. The spectral region of Hα-Cα correlations of A1 and A5 is reported in the absence of FGF8b (black) and at 0.5:1 (blue) and 1:1 (red) FGF8b:ARPCA ratios. D. Inhibition of HSPG/FGF8b/FGFR1 ternary complex formation by ARPCA. Data are the mean ± SEM of three determinations. **P < 0.01; ^#P < 0.001.