Recifercept structure with 3 Ig domains (I, II, III), the FGF binding site (FGF), the acid box (black box), disulfide bridges (S-S) and the first 13 amino acid of the intracellular domain of FGFR3 (shaded box) (A). Control BaF3, BaF3 stably overexpressing either FGFR3 IIIc wt or FGFR3 IIIc G380R are stimulated with increasing concentrations of hFGF1 (nM) in presence of 10μg/mL heparin sodium salt and proliferation measured after 72h (B). These cell lines are then stimulated with 0,6nM hFGF1 and increasing concentrations (nM) of Recifercept in presence of 10μg/mL heparin sodium salt, and proliferation measured the same way (C). Graphs are representive of three independent experiments.