Vitamin-D receptor (VDR): The vitamin D3 receptor (VDR) is an intracellular hormone receptor that specifically binds the active form of vitamin D (1, 25-dihydroxyvitamin D3 or calcitriol), which has been shown to promote differentiation and inhibit the proliferation of prostate cancer cells. The gene discussed is NR4A1; the disease is prostate carcinoma.