FIGURE 4.

Functional analysis of DRA promoter deletion constructs in response to ATRA treatment. Caco-2 cells were transiently transfected with full-length DRA promoter (p-1183/+114) and its progressive 5′ deletion constructs along with pCMVβgal vector. At 24 h post-transfection, cells were treated with 10 μm ATRA for 24 h. Cells were then harvested 48 h post-transfection and the promoter activity was measured by luciferase assay. Values were normalized to β-galactosidase activity to correct for transfection efficiency. Results are expressed as % of respective control for each promoter construct and represent mean ± S.E. of 3 separate experiments performed in triplicate. *, p < 0.05 compared with respective control taken as 100%.