CYP2R1 and hepatocellular carcinoma: Although the detailed mechanistic explanation for this linkage of VDR, VDBP, and CYP2R1 polymorphisms to the development of hepatocellular carcinoma was not given, the hepatic conversion of VD to 23(OH)D3, the plasma transportation of VD by VDBP, and the intracellular binding of VD with VDR might be affected by polymorphic changes in VDR, VDBP, and CYP2R1 genes.