Figure 1: Summary of the main insulin signaling pathways. GLUT-1 and -4: glucose transporter-1 and -4; Grb-2: growth receptor binding-2; GSK-3: glycogen synthase kinase-3; IR: insulin receptor; IRS-1 and -2: insulin receptor substrate-1 and -2; MAPK: mitogen-activated protein kinase; PDK-1: phosphoinositide-dependent kinase-1; PIP2: phosphatidyl-inositol diphosphate; PI3: phosphatidyl-inositol triphosphate; P: phosphate; PKC: protein kinase C; PP-1: phosphoprotein phosphatase-1; p70S6 K: protein 70 S6 kinase; p90rsk: protein 90 ribosomal S6 kinase; Shc: Src homology collagen; SHP-2: phosphatase with Src homology 2 domain; SoS: Son of Sevenless.