The biological actions of 1,25-Dihydroxyvitamin D3 are primarily mediated by the VDR,which belongs to the superfamily of steriod/thyroid hormone nuclear receptors.

• 1,25二羟维生素D3是维生素D的活性形式,它除了具有钙、磷代谢调节作用外,还能调节正常组织和肿瘤细胞的生长和分化。