Deletion analysis of the NGX6 promoter. (A) Schematic illustration of deletion constructs of NGX6 promoter. (B)Luciferase activity of the deleted constructs in Cos7 and HT-29 cells. PGL3-enhancer, PGL3-control and NGX6-promoter deleted constructs were transfected into Cos7 and HT-29 cells. All of the constructs were cotransfected with β-galactosidase vector for normalizing transfection efficiency. Data are the meas ± SD of three independent experiments. All the transfection experiments were repeated at least three times.