Transcription factor overexpression and L1CAM promoter luciferase activity. (A) Demonstration that E-boxes are essential for promoter 2 activity. In the minimally active promoter construct pGl3-L1-D the E-box (E1) was deleted and analysed in Ishikawa cells for promoter activity. (B) The ratio of Slug/Snail determines the outcome of promoter 2 activity. The pGl3-L1-A promoter constructs was co-transfected with different ratios of Slug in Ishikawa cells and promoter activity was determined after 48 h. Data ± SD of representative experiments from each n = 3 is shown. (*** p ≤ 0.001, **p ≤ 0.01, *p ≤ 0.05, n.s. not signicicant).