The superfamily of secreted insulin-like growth factor (IGF) binding proteins includes high-affinity IGF binding proteins (IGFBP) and low-affinity binding proteins referred to as IGFBP-like or IGFBP- related proteins (IGFBPL, IGFBP-rP) (1). IGFBPs form complexes with IGF-I and -II, modulating their activity and bioavailability by modifying their binding to cell receptors, cell surfaces, and the extracellular matrix (1-5). In addition to direct effects on activity and binding of IGFs, IGFBPs act as carriers for circulating IGFs, prolonging their half-lives, and creating IGF reservoirs in tissues (1, 3, 4). IGFBP-2 and other superfamily members contain N-terminal IGF-binding domains with 12 conserved cysteines, and C-terminal thyroglobulin type 1 domains with 6 conserved cysteines (1). The C-terminal domain mediates heparin binding, which is enhanced in the presence of IGFs and, in the case of IGFBP-2, contains an RGD sequence that promotes integrin-mediated cell attachment (1, 3, 5-9). IGFBP-2 affinity and extracellular matrix binding enhancement is stronger for IGF-II than IGF-I (4, 9).