FOXO3a and GFP-FOXO trigger a similar induction of luciferase activities. pGL-3xDBE or pGL-3xDBEmut were transiently co-transfected with plasmids encoding FOXO3a or GFP-FOXO3a into U2OS cells. U2foxRELOC cells that stably express the GFP-FOXO3a protein (9) were transiently transfected with pGL-3xDBE. LY294002 (20 μM, hatched bars) or DMSO (black bars) were added to the transfected cells six hours before processing the cells to assay the luciferase assay. The values are the means ± SEM of relative luciferase activities from three independent experiments performed in triplicates.