In each of four independent experiments, the test constructs and external positive control (pXP2 with an unrelated promoter for normalization) and negative control (pXP2 without a promoter fragment) were transfected in triplicate. Luciferase activity/β-galactosidase activity was calculated for each sample and then normalized to the average of the three external controls in the same experiment, with the average value of the external controls set to 100. Data are presented as mean relative luciferase activity ±1 standard error of the mean. Significance was determined by a t-test (two-tailed, unequal variance; Microsoft Excel). Negative controls averaged 0.8% of the positive control.
