VP16-E2 is a more potent transcriptional activator than Gal4-VP16. VP16-E2 is a more potent transcriptional activator than Gal4-VP16. A, a representation of the sequences used to drive VP16-E2 and Gal4-VP16 expression and the reporter gene used to monitor the transcriptional activation properties of the two proteins. B, a titration of the TERT-driven VP16-E2 and Gal4-VP16 plasmids was assayed for transcriptional activation of the luciferase reporter shown in A in 293T cells. C, a titration of the TERT-driven VP16-E2 and Gal4-VP16 plasmids was assayed for transcriptional activation of the luciferase reporter shown in A in MCF7 cells. D, a titration of the TERT-driven VP16-E2 and Gal4-VP16 plasmids was assayed for transcriptional activation of the luciferase reporter shown in A in C33a cells. All transcription results are presented as fold activation over the activity generated by the luciferase reporter by itself and are normalized to protein concentration. All experiments were carried out at least three times in duplicate. Bars, SE. A numerical summary of the transcription results is shown in Table 1A. The P values shown represent the result of t test analysis on at least three independent experiments. Maja L. Arendt et al. Mol Cancer Ther 2009;8:3244-3254 ©2009 by American Association for Cancer Research