PPAR- Agonists and Their Effects on IGF-I Receptor Signaling: Implications for Cancer
Figure 1
The IGF system: receptors, ligands, and signaling pathways. (a) Schematic representation of the major receptors and ligands involved in the IGF system. Insulin receptor isoforms (IR-A or IR-B) binds insulin with high affinity, while IGF-I receptor (IGF-IR) binds IGF-I and IGF-II (left). In cells expressing both IR and IGF-IR, IR hemireceptors may heterodimerize with IGF-IR hemireceptors, leading to the formation of hybrid IR/IGF-IRs (HRs), which bind IGF-I and IGF-II with high affinity and insulin with a much lower affinity (right). (b) The IGF system signaling pathways. Schematic representation of the two major signaling pathways involved in IGF system. IGF-I, IGF-II, and insulin bind to their cognate receptors, leading to the activation of the PI3K/Akt/mTOR pathway and of the Ras/Raf-1/MEK/ERK pathway.
