FIG. 2.

EGF stimulation induces TBP promoter activity. (A) EGF induces TBP promoter activity in a dose-dependent manner. JB6 cells were transiently transfected with 5 μg of the human TBP promoter-luciferase construct p−4500/+66hTBP-luc. Twenty-four hours after transfection, cells were incubated in 0.1% FBS-MEM with various concentrations of EGF overnight, as indicated. Protein lysates were prepared, and luciferase activity measurements were made as described in Materials and Methods. The change in TBP promoter activity was calculated relative to that with no EGF treatment. The results shown are based on at least three independent experiments. (B) The EGFR inhibitor AG 1478 blocks TBP promoter activity stimulated by EGF. Twenty-four hours after the cells were transfected with p−4500/+66hTBP-luc, the cells were pretreated with or without AG 1478 (0.5 μM) for 1 h and then incubated with or without EGF (12.5 ng/ml). The values shown are the means ± standard errors of the means of at least four independent experiments.