What are Growth Factors
Growth factors, which generally considered as a subset of cytokines, refer to the diffusible signaling proteins that stimulate cell growth, differentiation, survival, inflammation, and tissue repair. They can be secreted by neighboring cells, distant tissues and glands, or even tumor cells themselves. Normal cells show a requirement for several growth factors to maintain proliferation and viability. Growth advantage is often found for the cells which secrete a growth factor. Learn More.
History of Growth Factor Discovery
The first growth factor, nerve growth factor was discovered by Stanley Cohen and Rita Levi-Montalcini in 1952. Then, another nerve growth factor was purified from snake venom in 1959, and the first epidermal growth factor was isolated from the submaxillary gland of the mouse in 1962. Learn More.
Growth Factor Receptors
CGrowth factor receptors are transmembrane proteins which bind to specific growth factors and transmit the instructions conveyed by the factors to intracellular space. The growth factor receptors on cell surface are very common, and cells mainly contains receptors for several growth factors. Most receptors have a cysteine-rich region, which participate in signal transduction by receptor tyrosine kinase, e.g., the receptors fibroblast growth factor, vascular endothelial growth factor, epidermal growth factor, insulin-like growth factor, and platelet-derived growth factor, etc. Meanwhile, there are some receptors which mediate the signal transduction via receptor serine-threonine kinase, such as the receptor for transforming growth factor β. Learn More.
Growth Factor Signaling
When a growth factor and its receptor bind together, the receptor can either transiently exert its kinase activity or form a complex with an intracellular tyrosine or serine/threonine kinase. Subsequently, the activated receptors result in the activation of other proteins in the signaling pathway and the production of various second messengers. These signals are finally transmitted into the nucleus and induce the expression of specific genes. Learn More.