| | IGFBPs | Expression | Results of inhibiting IGFBP activity | Reference |
| | IGFBP-1 | Liver | It can induce or inhibit the IGF actions in many types of cells. As an example of the inhibiting activity of IGFBP-1, it inhibited IGF-I-induced growth in MCF-7 breast cancer cells. | [30, 157] |
| | IGFBP-2 | Liver, adipocytes, reproductive system, and central nervous system | IGFBP-2 level changes were associated with the development of different types of cancer including breast and prostate cancer. In prostate cancer, high level of serum IGFBP-2 was associated with low grade prostate cancer. | [189, 190] |
| | IGFBP-3 | Circulating carrier protein, expressed in many tissues | IGFBP-3 plays important role in different types of human cancers. IGFBP-3 can induce apoptosis by increasing the ratio of proapoptotic to antiapoptotic proteins in breast cancer cells. | [191] |
| | IGFBP-4 | Liver, bone tissue, and muscles | IGFBP-4 showed a strong inhibitory effect on IGF-1 by preventing the activation of the IGF-1R, when the IGFBP-4 is found in the tissue. Conversely, intravenous administration of IGFBP-4, in the presence of a protease, will promote cellular proliferation. | [79, 192–195] |
| | IGFBP-5 | Mammary glands | In breast cancer, IGFBP-5 induced apoptosis and inhibited cellular differentiation in an IGF-dependent manner. | [196, 197] |
| | IGFBP-6 | Epithelial layer of human bronchial organ | It can inhibit IGF-2 activity mediated through the IGF-1R, including proliferation, differentiation, migration, and survival in different cell lines. | [198, 199] |
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