Insulin-like growth factor 1 (IGF-1 or IGF-I), also known as somatomedin C, is the dominant effector of growth hormone and is structurally homologous to proinsulin. Human IGF-1 is synthesized as two precursor isoforms with N- and alternate C‑terminal propeptides (1). These isoforms are differentially expressed by various tissues (1). The 7.6 kDa mature IGF‑1 is identical between isoforms and is generated by proteolytic removal of the N- and C‑terminal regions. Mature human IGF-1 shares 94% and 96% aa sequence identity with mouse and rat IGF-1, respectively (2), and exhibits cross-species activity. It shares 64% aa sequence identity with mature human IGF2. Circulating IGF-1 is produced by hepatocytes, while local IGF-1 is produced by many other tissues in which it has paracrine effects (1). IGF-1 induces the proliferation, migration, and differentiation of a wide variety of cell types during development and postnatally (3). IGF-1 regulates glucose and fatty acid metabolism, steroid hormone activity, and cartilage and bone metabolism (4‑7). It plays an important role in muscle regeneration and tumor progression (1, 8). IGF-1 binds IGF1R, IGF2R, and the insulin receptor, although its effects are mediated primarily by IGF1R (9). IGF-1 association with IGF binding proteins increases its plasma half‑life and modulates its interactions with receptors (10).