Insulin-like growth factor binding proteins (IGFBPs) play an essential role in modifying the action of insulin-like growth factor (IGF) in many cell types. There are six structurally related but genetically distinct members of this family. IGFBP2 is the second most abundant circulating IGFBP and is found in other biofluids and tissues in many vertebrates. Serum IGFBP2 levels are elevated in response to shock, fasting, hypoxemia, or post-traumatic injury, suggesting complex regulation of IGFBP2 expression. IGFBP2 is overexpressed in many malignant tumors and correlates with tumor malignancy, suggesting that IGFBP2 may be involved in tumorigenesis. During development, IGFBP-2 is expressed in several tissues. The highest level of expression is found in the central nervous system (CNS). It is also highly expressed in the adult CNS and many reproductive tissues.