Insulin-like growth factor-binding protein 3 is also known as IGFBP3, is a protein that, in humans, is encoded by the IGFBP3 gene. IGFBP3 forms a ternary complex of about 140 ~150 kDa with IGF1 or IGF2 and a glycoprotein insulin-like growth factor acid-labile subunit (ALS), thus alter the interaction of IGFs with their cell surface receptors. IGFBP3 exerts either proapoptotic or growth stimulatory effects depending upon the cellular context. Studies have shown that IGFBP3 can leads to the induction of apoptosis dependent or independent of the IGF-IGF receptor axis, accordingly acts as a negative regulator of tumorigenesis and progressing in certain carcinomas. The highest expression level is found in the nonparanchymal cells of the liver. Expression levels are also higher during extrauterine life and peak during puberty.
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