EC proliferation in the presence of FGF-2 mutants. (A) ECs were plated on gelatin-coated wells in McCoy 5A medium supplemented with 20% FBS, 50 μg/mL ECGS, and 100 μg/mL heparin and allowed to adhere for 6 hours. The cells were then washed twice with McCoy medium and incubated in serum-free medium containing 1% Nutridoma, 1 μCi (0.037 MBq) ³H-thymidine with 25 ng/mL of wtFGF-2 or FGF-2 mutants (2212 or 221^*2) in the presence or absence of 100 μg/mL fibrinogen (FBG) for 24 hours. Isotope incorporated into DNA was precipitated with TCA, collected by vacuum filtration, and measured by scintillation counting. (B) To characterize specificity, the same experiment was conducted comparing the response with 100 μg/mL fibrinogen, gelatin (GEL), or vitronectin (VN). Neither gelatin nor vitronectin significantly increased the response to FGF-2. Results are the mean ± SD of 3 different experiments.