A: FGF-16 competes with FGF-2 for binding specifically at FGF receptor (R)-1. H9c2 myoblasts stably transfected with FGFR-1 were incubated with 125I-labeled FGF-2 (1.0 ng/ml) at 37°C for 1 h in the presence of increasing amounts of unlabeled FGF-16 (representing 77-, 154-, 295-, 606-, and 1,227-fold molar excess). Absolute value for control mean ± SE was 1,164.25 ± 161.13 cpm (n = 4). *P < 0.05 and **P < 0.01, compared with control (Dunnett posttest). B: FGF-16 competes with FGF-2 for receptor binding in cardiac myocytes. Cardiac myocytes were incubated with 125I-labeled FGF-2 (1.1 ng/ml) in the presence of 100- or 1,000-fold molar excess of cold competitor (FGF-2 or FGF-16, as indicated). Relative counts per minute values are shown for each group. Absolute means ± SE for control group (no competition) are 411.5 ± 30 (n = 6). **P < 0.01, compared with control (Dunnett posttest).