FIG. 4.

TFII-I enhances c-fos promoter activation. (A) NIH 3T3 cells were transfected with the wild-type (WT) c-fos/Luc reporter constructs and TFII-I. For control cultures, the empty vector of TFII-I expression plasmid was cotransfected with reporter constructs. Cells were serum starved for 36 h in 0.5% CS and then stimulated for 4 h with 10% CS, 50 ng of TPA per ml, 10 μM LPA, or 25 ng of PDGF-BB per ml in DMEM. Cell extracts were then processed for luciferase activity. Relative luciferase activities shown here are from a representative experiment, and similar results were obtained from four further independent experiments. All transfections were performed in duplicate for each experiment, and the values between the duplicates were within 10% of the mean. (B) TFII-I fails to transactivate the TK and c-fos basal promoters. The TK/Luc, c-fos basal (−57)/Luc, and wild-type c-fos/Luc reporter constructs were transfected into NIH 3T3 cells with or without TFII-I. Unstimulated or 10% CS-stimulated cells were then analyzed for luciferase activity. The data shown are the average of three independent experiments, and the standard deviations between experiments were on average 30% of the values shown here. All transfections were performed in duplicate for each experiment, and the values between the duplicates were within 10% of the mean.