FIG. 1.

Mutational analysis of the secretin promoter. HIT cells were transiently transfected with a secretin-luciferase reporter gene (Materials and Methods) without (wild type [WT]) or with transversion mutations (10 to 13 bp) at different positions (shown by the numbers under each bar) including the TATA box (A) or with 4-bp transversion mutations at different positions (C). Luciferase activity was measured in cell extracts 16 h later. Results are expressed aspercentages relative to the wild-type reporter and are the means ± standard errors of the means (SEM) normalized for transfection efficiency for at least three independent experiments. (B) The mutationally sensitive sequences present in the promoter region are highlighted with a black background.