Relative binding of anti-R-125224 antibody and biotin-R-125224 in the presence of antigens (control human IgG, R-125224, Fab of R-125224 and m-HFE7A) at doses of 0.4 (A) and 1.2 mg·kg−1 (B). IC50 values (competitive antigen/biotin-R-125224) of R-125224, Fab of R-125224 and m-HFE7A were 0.496, 1.02, and 0.664 respectively.