<p>(A) Deletion analysis of the <i>VDR</i> promoter-reporter construct. VDR-1 kb, VDR-500 bp, VDR-250 bp and VDR-120 bp promoter-reporter plasmids (300 ng each) were cotransfected with 400 ng of the Osx expression plasmid in HEK293 cells. Twenty-four hours post-transfection, cell extracts were prepared and analyzed for luciferase activity and normalized to β-galactosidase activity. (B) Two GC-rich elements in VDR-120 are responsible for <i>VDR</i> promoter reporter activation by Osx. The promoter mutants VDR-M1, VDR-M2 and VDR-M12 were transfected into HEK293 cells and analyzed as described in panel A. Luciferase activity was normalized by β-galactosidase activity. (C) A diagram of the proximal 120 bp region of the mouse VDR promoter. A 5′ primer and 3′ primer were used to subclone the VDR-120 bp promoter reporter plasmid. M1 refers to point mutations of VDR-M1, and M2 refers to point mutations of VDR-M2. VDR-M12 in (B) contains both M1 and M2.</p
