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