IGFBP6 and cancer: Second, the IGF axis includes the polypeptide ligands IGF1 and IGF2, the IGF receptors, and six binding IGF proteins (IGFBP1-IGFBP6), there are relation between many members, some single-nucleotide polymorphisms of familiar members, such as polymorphisms of, IGFBP2 and IGFBP3, may exert their complex and interacting functions with each other, which could affect the effects of A-202C polymorphism in the pathogenesis of cancer.