A-F) 10 million HEK-293 or Saos-2 cells were transfected with pGL2 control vector, full-length E2F1 promoter construct, Flag-E2F6, either increasing doses of EBNA3C or E2F6 expression plasmids. Thirty-six hours post-transfection, cells were harvested and carried out for luciferase reporter assays. Expression of transfected constructs were detected by western blot. G-H) 10 million HEK-293 or Saos-2 cells were transfected with pGL2 control vector, full-length E2F1 promoter construct, Flag-E2F1, Flag-E2F6, and EBNA3C expression plasmids. Luciferase reporter assays were carried out at 36 hours post-transfection as above. Expression levels of transfected constructs were also examined by western blot.