Table 1.

Effect of cell density on stimulation of FGF-2 promoter activity by growth factors and PMA

Treatment	FGF-2luciferase		RSVluciferase
	Low	High	Low	High
Control	1.00 ± 0.15	0.054 ± 0.01	1.0 ± 0.15	0.5 ± 0.13
EGF	2.79 ± 0.57a	0.050 ± 0.006
FGF-2	2.70 ± 0.34a	0.03 ± 0.006
PMA	4.62 ± 1.20a	0.08 ± 0.04	2.6 ± 0.04	1.1 ± 0.26

Astrocytes were transfected with (−650/+314)FGF-2luciferase or control RSVluciferase constructs as described in MATERIALS AND METHODS. After electroporation, cells were seeded into 12-well dishes at high (100% confluence) or low density (∼30% confluence). Attached cells were washed twice with PBS, and serum-free medium containing 0.25% BSA was added. Twenty-four hours later the cells were treated with EGF (5.0 × 10⁻⁹ M), 18-kDa FGF-2 (5 × 10⁻¹⁰ M), or PMA (100 nM) for an additional 24 h. The results are expressed relative to control luciferase activity in low-density cultures. Numbers for FGF-2luciferase represent mean ± SEM of 8–18 samples from two or three independent experiments. Three-way analysis of variance showed a significant interaction between growth factors or PMA and cell density (p < 0.002). Numbers for RSVluciferase from a single representative experiment and are shown for comparison. 

^aPosthoc analysis: difference from control (p < 0.005).