A growth factor is a naturally occurring substance that plays a crucial role in regulating various cellular processes. These include cell proliferation, wound healing, and cellular differentiation. Generally considered a subset of cytokines, growth factors are diffusible signaling proteins that influence cell growth, differentiation, survival, inflammation, and tissue repair.

Growth factors can be secreted by various sources, including neighboring cells, distant tissues, glands, and even tumor cells. They are essential for normal cell function, as many cells require several growth factors to maintain proliferation and viability. Cells that secrete growth factors often gain a growth advantage.

Growth factors exert their effects through endocrine, paracrine, or autocrine mechanisms, but they typically act locally due to their short half-lives and limited diffusion in intercellular spaces. The signaling process usually begins when a growth factor binds to its specific receptors on the surface of target cells. The outcome of this interaction depends on factors such as the type of receptors, the number of target cells, and the subsequent intracellular signal transduction.

Additionally, external factors like the binding ability of a growth factor to extracellular matrices (ECM), ECM degradation, and the concentration of the growth factor can influence the cellular response to a specific growth factor.