FIGURE 5.

Functional analyses of the AP-1 site in the GATA-4 promoter. A, luciferase activity resulting from undifferentiated (day 0; open bars) or differentiated (day 4; black bars) P19 CL6 cells, transfected with either a WT GATA-4 promoter-luciferase plasmid (Wt) or the same plasmid containing a mutated AP-1-binding site (Mut) as indicated. B, luciferase activity resulting from undifferentiated P19CL6 cells, again transfected with either the WT or mutated promoter-luciferase constructs and additionally transduced with AdNox4 or AdβGal. In all cases, luciferase activity was measured 24 h after transfection and transduction and was normalized to that of the co-transfected SV40-Renilla luciferase vector and expressed as RLU. C and D, histograms depicting the fold induction, relative to controls, of the WT and mutated GATA-4 promoter activities upon either differentiation or Nox4 transduction, respectively. All data are presented as mean ± S.E. *, p < 0.05. n.s., not significant.