Vitamin D directly regulates Mdm2 gene expression in osteoblasts

► Physiological levels of vitamin D can induce an increase in Mdm2 expression. ► Mdm2 and VDR levels are increased after vitamin D treatment. ► Mdm2-P2 initiated transcripts are increased with vitamin D treatment. ► A VDR binding site was detected on the Mdm2 promoter and was bound by VDR. ► Activation of Mdm2 by vitamin D requires the presence of wild type p53.