APA Dictionary of Psychology

any of a group of proteins, naturally produced by various tissues, that stimulate and regulate cell growth and survival. Different growth factors affect different cells; for example, erythropoietin, which is produced by the kidneys, affects erythrocytes (red blood cells), and epidermal growth factor, which is produced by various glands, affects epithelial cells, among others. Therapeutic uses of growth factors include administration of erythropoietin to treat anemia. Growth factors may have a role in the development and growth of some cancers, and chemicals that block their effects may be used as anticancer therapy.