insulinlike growth factor
(formerly termed somatomedin C), the most important somatomedin for postnatal growth; it is produced in the liver, kidney, muscle, pituitary, the gastrointestinal tract, and chondrocytes. IGF-I is a basic protein (7600 MW) that circulates bound to six distinct IGF binding proteins (IGF-BPs), which increase the half-life of circulating IGF-I to 3–18 hours, as compared with the half-life of 20–30 minutes for unbound hormone. Local tissue generation of IGF-I/SM-C, particularly in bone, may play an important role in growth mediation through its paracrine effects.
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Examples: glitazone, GI cocktail, etc.