Differential regulation of TGF-β1 treatment on both L1CAM promoter regions. Hec-1A and ECC-1 cells were treated for 5 days with TGF-β1 (10 ng/ml) prior to luciferase transfection. Luciferase levels were analysed 48 h after transfection using a dual luciferase assay. (A) Hec-1A cells show no increased luciferase activity upon stimulation with TGF-β1 on promoter 1, but on promoter 2. (B) ECC-1 cells show an enhanced luficerase activity on promoter 1 when pretreated with TGF-β1, but not on promoter 2. Data ± SD of a representative experiment from n = 2 is shown.