Fig. 2.

Effects of EGF on hSERT promoter activities in Caco-2 cells. A: hSERTp1 is active in Caco-2 cells. Caco-2 and HEK-293 cells were transiently cotransfected with the hSERTp1 promoter construct along with the β-galactosidase mammalian expression vector. Promoter activity was measured by firefly luciferase assay and represented as relative luciferase units normalized to β-galactosidase activity to adjust for transfection efficiency. The activity of the pGL2 empty vector alone in Caco-2 cells or HEK-293 cells is represented as 100%. hSERTp1 was highly active in Caco-2 cells. Results were obtained from 3 separate experiments and are expressed as means ± SE. *P < 0.0001 compared with empty vector. B: effect of EGF on activity of hSERTp1 and hSERTp2. Caco-2 cells were transiently cotransfected with hSERTp1 or hSERTp2 fragments along with β-galactosidase vector to adjust for transfection efficiency. Twenty-four hours after transfection, cells were incubated with 10 ng/ml EGF for another 24 h. hSERTp1 exhibited higher activity than hSERTp2 in Caco-2 cells. EGF increased the activity of both hSERTp1 and hSERTp2. Data are represented as % of control and represent means ± SE of 5 or 6 different experiments performed in triplicate. *P < 0.05 compared with control.