Growth factors

A growth factor is an extracellular protein which is able to trigger a cell to grow and therefore cause an increase in the cells mass. They do this by encouraging the synthesis of macromolecules such as proteins. In addition growth factors inhibit the degradation of such macromolecules. Other functions of the growth factor consist of stimulating the cells to survive and proliferate. Two examples of growth factors are platelet-derived growth factor (PDGF) and epidermal growth factor (EGF). PDGF has the ability to stimulate many types of cell to divide, for instance smooth muscle cells, neurological cells as well as fibroblasts. Correspondingly, EGF does not only act upon epidermal cells but also on epithelial and nonepithelial cells.