Section outline

    • Most of the IGF-I exists bound to IGFBPs. IGFBPs are capable of inhibiting IGF-I from binding to the receptor or/and promoting the effects of IGF-I by transporting it to target cells and passing it to the receptor while protecting it from degradation. Types 1-6 of IGFBPs are known; each of these exhibits different IGF-I inhibitory / promoting functions. The activity of the IGF-I is strictly regulated by multiple IGFBPs in this way, and IGFBP is an important element in understanding the growth regulation mechanism.