Fig. 3.

Major components of IGF-R-linked signaling pathways. IRS-1 represents a central docking protein involved in the activation of MAP kinase and PI3 kinase pathways. Like IRS, Shc can be phosphorylated directly as a consequence of the receptor kinase. GF-R, growth factor receptor; MEK-K, MEK kinase; p, phosphorylation; Sos, Son of Sevenless. [Reprinted from Clemmons DR (2001) IGF-1 receptor-mediated signal transduction, in Targets for Growth Hormone and IGF-1 Action (Bouillon R ed), pp 17–28, Bioscientifica Ltd., Bristol, UK. Copyright © 2001 Bioscientifica Ltd. Used with permission.]