Vitamin D binding protein (VitaminDBP), also known as GC (group specific component) globulin, belongs to the albumin gene family along with human serum albumin and alpha fetoprotein. It has multiple functions and exists on the surface of plasma, ascites, cerebrospinal fluid, and many types of cells. It binds to vitamin D and its metabolites, transporting them to target tissues. As a macrophage activating factor derived from Gc protein, VitaminDBP can be used for cancer treatment to activate macrophages to resist tumor cells.