A protein made by the body that stimulates the growth of many types of cells. IGF is similar to insulin (a hormone made in the pancreas). There are two forms of IGF called IGF-1 and IGF-2. Higher than normal levels of IGF-1 may increase the risk of several types of cancer. IGF is a type of growth factor and a type of cytokine.

(insulinlike growth factor) Insulin-like polypeptides made by the liver and some fibroblasts and released into the blood when stimulated by somatotropin; they cause sulfate incorporation into collagen, RNA, and DNA synthesis, which are prerequisites to cell division and growth of the organism.

(insulin-like growth factor) Bound to IGFBPs in the circulation, Insulin-Like Growth Factors (IGFs, Somatomedins) are a family of extracellular signaling peptides (potential autocrine ligands) involved in mediation of growth hormone action, stimulation of insulin action, and growth and development. The three main somatomedins are Somatomedin C (IGF1), Somatomedin A (IGF2), and Somatomedin B. Single chain IGFs I and II share about 47% amino acid homology with insulin (INS) and 31% with relaxin.