![Fig. 1. (A) PF4 dose-dependently inhibits bFGF- (left) and EGF-induced (right) DNA synthesis in endothelial cells. HUVEC were plated in 96-well dishes as described in Materials and Methods. After reaching confluence they were kept in starvation medium for 24 hours, then stimulated with growth factor in the presence of the indicated concentrations of PF4. [3H]-thymidine incorporation was evaluated after 20 hours and was expressed as a percent of the maximum incorporation achieved with the highest dose of growth factor in the absence of PF4 (ordinate). Data shown are mean values ± SE of three independent experiments performed in triplicate. (B) Heparin and protamine inhibit bFGF- but not EGF-stimulated proliferation of HUVEC. HUVEC were treated as in (A), except that bFGF was used at 2 ng/mL, EGF at 20 ng/mL, and PF4 at 2 μg/mL, in the presence of the indicated concentrations of heparin (H) or protamine. Data are expressed as a percent of the maximum incorporation achieved with the highest dose of growth factor in the absence of PF4 (ordinate), and are mean values ± SE of three independent experiments performed in triplicate.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/93/1/10.1182_blood.v93.1.25/5/blod40147001ax.jpeg?Expires=1724235394&Signature=RJ03QUbPPlnqjKPSzSLxw7ZZ8ntv95VwZ0tQpGNWWtolwPiG2dSKUG5okaf27januhwFVZHa2hgqML9hugJaDWMZscXlavg7P1LVzVWjnnt1QJfknZHEOZCC~~U44IKiqXWiNA7QkUQACZjKwo~-kzwPG7TAa2pkZ1de7aKGADBZOP~PNtWnUInNGAqiHNVdreQ92D9SwTVX-ZyzhZy9D1MNrn7FPngZRB77XxVz3M5k5Gd5XqSSzLNVkUARBpo5EDDYuAo4CJFvfXpN8~xvCbDtd2r4pCZH1Sg~u3UL4vfN7nVqrfG-jl48A9Y8a5MedLFTllsVOjKQVvIMNutv7g__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
(A) PF4 dose-dependently inhibits bFGF- (left) and EGF-induced (right) DNA synthesis in endothelial cells. HUVEC were plated in 96-well dishes as described in Materials and Methods. After reaching confluence they were kept in starvation medium for 24 hours, then stimulated with growth factor in the presence of the indicated concentrations of PF4. [3H]-thymidine incorporation was evaluated after 20 hours and was expressed as a percent of the maximum incorporation achieved with the highest dose of growth factor in the absence of PF4 (ordinate). Data shown are mean values ± SE of three independent experiments performed in triplicate. (B) Heparin and protamine inhibit bFGF- but not EGF-stimulated proliferation of HUVEC. HUVEC were treated as in (A), except that bFGF was used at 2 ng/mL, EGF at 20 ng/mL, and PF4 at 2 μg/mL, in the presence of the indicated concentrations of heparin (H) or protamine. Data are expressed as a percent of the maximum incorporation achieved with the highest dose of growth factor in the absence of PF4 (ordinate), and are mean values ± SE of three independent experiments performed in triplicate.
