VDR and colorectal cancer: Most importantly, a large portion of advanced colorectal cancer patients lack expression of the VRD gene SNAI1 (snail family transcriptional repressor 1) and SNAI2 (snail family transcriptional repressor 2) proteins, which directly bind and block transcription of the VDR promoter (8, 9), and supplementing these patients with vitamin D in the early stage of colorectal cancer is associated with positive outcomes but not in the advanced stages (5).