Editing Insulin-like growth factor 1 (section)

=== The IGF system ===

IGF-1 is part of the insulin-like growth factor (IGF) system.<ref name="García-Mato_2021" /> This system consists of three [[Ligand (biochemistry)|ligands]] ([[insulin]], IGF-1 and [[Insulin-like growth factor 2|IGF-2]]), two [[tyrosine kinase receptors]] ([[insulin receptor]] and [[IGF-1R]] receptor) and six ligand binding proteins ([[Insulin-like growth factor-binding protein|IGFBP]] 1–6).<ref name="García-Mato_2021">{{cite journal | vauthors = García-Mato Á, Cervantes B, Murillo-Cuesta S, Rodríguez-de la Rosa L, Varela-Nieto I | title = Insulin-like Growth Factor 1 Signaling in Mammalian Hearing | journal = Genes | volume = 12 | issue = 10 | pages = 1553 | date = September 2021 | pmid = 34680948 | pmc = 8535591 | doi = 10.3390/genes12101553 | doi-access = free }}</ref> Together they play an essential role in [[Cell proliferation|proliferation]], [[Cell survival|survival]], regulation of [[cell growth]] and affect almost every [[organ system]] in the body.<ref>{{cite journal | vauthors = Annunziata M, Granata R, Ghigo E | title = The IGF system | journal = Acta Diabetologica | volume = 48 | issue = 1 | pages = 1–9 | date = March 2011 | pmid = 21042815 | doi = 10.1007/s00592-010-0227-z | s2cid = 24843614 }}</ref>

Similarly to IGF-1, [[IGF-2]] is mainly produced in the [[liver]] and after it is released into [[Blood circulation|circulation]], it stimulates growth and cell proliferation. IGF-2 is thought to be a [[Fetus|fetal]] growth factor, as it is essential for a normal [[Human embryonic development|embryonic development]] and is highly [[Gene expression|expressed]] in embryonic and [[Infant|neonatal]] [[Tissue (biology)|tissues]].<ref>{{cite book | vauthors = Winston BW, Ni A, Aurora RC | chapter = Insulin-like Growth Factors | veditors = Laurent GJ, Shapiro SD | title = Encyclopedia of Respiratory Medicine |date=2006 |pages=339–346 |doi=10.1016/B0-12-370879-6/00453-1 | isbn = 978-0-12-370879-3 | quote = GF-II appears to be essential for normal embryonic development and, as such, IGF-II is thought to be a fetal growth factor. IGF-II is highly expressed in embryonic and neonatal tissues and promotes proliferation of many cell types primarily of fetal origin.  }}</ref>