Figure 1.

The insulin-like growth factor 1-signaling pathway in cells. Insulin-like growth factor 1 activates both phosphatidylinositol 3-kinase/Akt and Ras/mitogen-activated protein kinase pathway resulting in cell proliferation, increased protein synthesis, and increased glucose metabolism. Phosphatidylinositol 3-kinase/Akt activates nuclear factor-κB for cell survival and inhibits apoptosis through inhibition of BAD and FKHR. Insulin-like growth factor-binding proteins modulate the bioavailability of insulin-like growth factor through direct binding in the extracellular space. Insulin-like growth factor-binding proteins also exert several insulin-like growth factor-independent effects through direct interaction with cell membrane-bound proteins, such as integrins