IGF1 (also somatomedin C) is an insulin-like growth factor hormone that is produced by the liver after growth hormone (GH) stimulation. It is similar in structure to insulin. It is important for childhood growth and regulates [1-14C]-2-deoxy-D-glucose (2DG) transport and glycogen synthesis in osteoblasts. IGF1 is effective at stimulating glucose transport, glycogen and DNA synthesis, and glucose uptake at much lower concentrations than insulin. It is also thought to play a role in synapse maturation. Disorders involving IGF1 include Laron dwarfism, where an absence of IGF1 produces growth failure, as well as acromegaly, where excess growth hormone and IGF1 lead to metabolic dysfunction. The inhibition of binding of IGF1 to its receptor IGF1R is also an anti-tumor therapy for cancers that depend on activating mutations in the downstream PI3K-AKT-mTOR pathway. In immunohistochemistry, IGF1 has extracellular and secreted positivity in plasma and is found in all tissues throughout the body. References: Nat Rev Endocrinol. 10 (4): 243–8. doi:10.1038/nrendo.2014.21. PMID 24566817; Endocrinology and metabolism clinics of North America. 2012. 41(2): 335-50, DOI:10.1016/j.ecl.2012.04.014;