Figure 4.

RORα repression of the OC promoter is dominant over VitD activation. ROS 17/2.8 cells were transfected with a luciferase reporter gene driven by either −344/+34 (OC-344-luc) or −890/+34 (OC-890-luc) of the human OC promoter together with an expression vector for RORα (ratio 2:1 μg) (gray bars) or without (black bars). When indicated, the cells were incubated with 10 nM vitamin D. Luciferase activity was assayed in cells from 6-well plates and related to the activity in cells transfected with an empty expression plasmid. The results were normalized to the protein content. Shown are the mean ± SD of three experiments, each carried out with triplicate analyses.