Effect of PF-4–derived peptides on FGF-2 dimerization. 10 ng ¹²⁵I-FGF-2, 500 ng unlabeled FGF-2 are incubated in the presence or absence of 50 ng heparin with fixed (10 μmol/L) or increasing concentrations of the different PF-4–derived peptides. Dimerization experiments were performed as indicated in Materials and Methods. (A) Increasing concentrations of peptide 47-70 in the absence of heparin (lane 1: control, lane 2: 2.6 μmol/L, lane 3: 5.4 μmol/L, lane 4: 10.8 μmol/L, lane 5: 21.4 μmol/L, lane 6: 42.7 μmol/L, lane 7: 87 μmol/L, lane 8: 134.5 μmol/L); (B) increasing concentrations of peptide 47-70 in the presence of heparin (lane 1: control with heparin, lane 2: 5.4 μmol/L, lane 3: 10.8 μmol/L, lane 4: 21.4 μmol/L, lane 5: 42.7 μmol/L, lane 6: 87 μmol/L, lane 7: 134.5 μmol/L) ; C, fixed concentrations (10 μmol/L) of various PF-4–derived peptides (lane 1: control without heparin, lane 2: control with heparin, lane 3: peptide 34-58, lane 4: peptide 47-58, lane 5: peptide 58-70, lane 6: peptide 17-58).