FIGURE 6.

Mutation of the C/EBPβ binding site (–79/–73) inhibits the activation of 1α(OH)ase transcription mediated by CT. AOK-B50 cells were transfected with 0.3 μg of mouse 1α(OH)ase (–85/+22) promoter (wild type (WT) or mutant (MT)) or 1α(OH)ase (–1651/+22) promoter (wild type or mutant). After 24 h, cells were treated with vehicle or 100 nm calcitonin (CT) for another 24 h. 1α(OH)ase promoter activity was measured by firefly luciferase activity/protein concentration and represented as -fold induction (mean ± S.E.) by comparison to basal levels (3–5 observations/group). *, p < 0.05 compared with wild type, calcitonin-treated.