Figure 1.

Mutational analysis of the secretin gene E box. A series of secretin-luciferase reporter gene constructions with different 4-bp transversion mutations in the secretin E box and upstream sequences was transiently transfected into HIT (solid bars) or STC1 (striped bars) cells. Luciferase activity was measured in cell extracts 20 h later. Results are expressed (in percent) relative to the activity of the wild-type reporter and are the mean ± SEM after correction for relative transfection efficiency for at least three individual transfection experiments done in triplicate. The sequence of the unmodified (WT) is shown at the bottom, with the changed nucleotides in mutants m1 through m5 indicated. The E-box sequence is highlighted. ∗, Values different from the WT, P < 0.001.