Fig. 3.

A: effect of c-Fos or c-Jun overexpression on Pgp promoter activity in Caco-2 cells. Caco-2 cells were transiently cotransfected with the Pgp promoter construct along with c-Fos and c-Jun mammalian expression vectors. Control cells were transfected with empty vector (EV) for c-Fos/c-Jun expression vector (pcDNA3.1) and Pgp promoter. At 24 h posttransfection, cells were harvested, and promoter activity was measured by luciferase assay. Values were normalized to β-galactosidase activity to correct for transfection efficiency. Values are means ± SE of 4 separate experiments. **P < 0.001 vs. EV. B: effect of c-Fos and c-Jun overexpression on Pgp mRNA expression in Caco-2 cells. Caco-2 cells were transiently cotransfected with the Pgp promoter construct along with c-Fos and c-Jun mammalian expression vectors. Control cells were transfected with empty vector for c-Fos/c-Jun expression vector (pcDNA3.1) and Pgp promoter. Total RNA was extracted from the tranfected cells, and 100 ng were amplified with multidrug resistance 1 (MDR1) or GAPDH gene-specific primers using 1-step RT-PCR mix containing SYBR Green fluorescence dye for real-time PCR quantitation. Relative abundance of MDR1 mRNA from empty vector and c-Fos/c-Jun-transfected Caco-2 cells was normalized to GAPDH mRNA (internal control). Data were quantified by densitometric analysis. Values are means ± SE of 3 independent experiments. **P < 0.001 vs. EV.