c-Myc/Max and USF1/USF2 differentially transactivate the promoter. (A) HepcP1.1-luc (100 ng) was transfected into BHK cells alone or with 100 ng c-Myc, Max, or c-Myc and Max. (B) HepcP1.1-luc was transfected with or without USF1, USF2 (100 ng each), or both. In the latter, various ratios of USF1 and USF2 were also cotransfected into BHK cells with HepcP1.1-luc. Fold activation in panels A and B was calculated with respect to the activity of HepcP1.1-luc alone. (C) HepcP1.1-luc (100 ng) was transfected into BHK cells alone or with 100 ng USF1 or USF2, and with increasing concentrations of dominant negative mutant USF1, A-USF, or (D) USF2 dominant-negative mutant, USF2ΔB. All transfections were performed in duplicate and included pSVβgal as internal control; luciferase levels were normalized to βgal activity. Fold repression by A-USF or USF2ΔB (C-D) was expressed with respect to the activity of HepcP1.1-luc in the presence of either USF1 or USF2. Data are representative of 3 independent experiments, and are plotted as means ± SEM. *P < .05; **P < .005; ***P < .001; determined by 1-way ANOVA and Student-Newman-Keuls multiple-comparisons test.