A growth factor is a naturally occurring substance capable of stimulating cell proliferation,

wound healing Wound healing refers to a living organism's replacement of destroyed or damaged tissue by newly produced tissue. In undamaged skin, the epidermis (surface, epithelial layer) and dermis (deeper, connective layer) form a protective barrier again ...

, and occasionally

cellular differentiation Cellular differentiation is the process in which a stem cell alters from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellular ...

. Usually it is a secreted

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

or a

steroid hormone A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typically made in the adrenal cortex, hence ''cortico-'') and sex steroids (typically made in the gonads or placenta). Wi ...

. Growth factors are important for regulating a variety of cellular processes. Growth factors typically act as

signaling In signal processing, a signal is a function that conveys information about a phenomenon. Any quantity that can vary over space or time can be used as a signal to share messages between observers. The ''IEEE Transactions on Signal Processing'' ...

molecules between cells. Examples are

cytokine Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...

s and

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...

s that bind to specific

receptors Receptor may refer to: *Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a n ...

on the surface of their target cells. They often promote cell differentiation and maturation, which varies between growth factors. For example, epidermal growth factor (EGF) enhances osteogenic differentiation, while

fibroblast growth factor Fibroblast growth factors (FGF) are a family of cell signalling proteins produced by macrophages; they are involved in a wide variety of processes, most notably as crucial elements for normal development in animal cells. Any irregularities in their ...

s and

vascular endothelial growth factor Vascular endothelial growth factor (VEGF, ), originally known as vascular permeability factor (VPF), is a signal protein produced by many cells that stimulates the formation of blood vessels. To be specific, VEGF is a sub-family of growth factors, ...

s stimulate blood vessel differentiation (

angiogenesis Angiogenesis is the physiological process through which new blood vessels form from pre-existing vessels, formed in the earlier stage of vasculogenesis. Angiogenesis continues the growth of the vasculature by processes of sprouting and splitting ...

Comparison to cytokines

''Growth factor'' is sometimes used interchangeably among scientists with the term ''

.'' Historically, cytokines were associated with hematopoietic (blood and lymph forming) cells and

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

cells (e.g.,

lymphocyte A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic ad ...

s and tissue cells from

spleen The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .

thymus The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus cell lymphocytes or ''T cells'' mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. ...

, and

lymph node A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that inclu ...

s). For the

circulatory system The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

and

bone marrow Bone marrow is a semi-solid tissue found within the spongy (also known as cancellous) portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production (or haematopoiesis). It is composed of hematopoietic ce ...

in which cells can occur in a liquid suspension and not bound up in solid tissue, it makes sense for them to communicate by soluble, circulating protein

molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

s. However, as different lines of research converged, it became clear that some of the same signaling proteins which the hematopoietic and immune systems use were also being used by all sorts of other cells and tissues, during development and in the mature organism. While ''growth factor'' implies a positive effect on cell proliferation, ''cytokine'' is a neutral term with respect to whether a molecule affects proliferation. While some cytokines can be growth factors, such as

G-CSF Granulocyte colony-stimulating factor (G-CSF or GCSF), also known as colony-stimulating factor 3 (CSF 3), is a glycoprotein that stimulates the bone marrow to produce granulocytes and stem cells and release them into the bloodstream. Functiona ...

and

GM-CSF Granulocyte-macrophage colony-stimulating factor (GM-CSF), also known as colony-stimulating factor 2 (CSF2), is a monomeric glycoprotein secreted by macrophages, T cells, mast cells, natural killer cells, endothelial cells and fibroblasts that ...

, others have an inhibitory effect on

cell growth Cell growth refers to an increase in the total mass of a cell, including both cytoplasmic, nuclear and organelle volume. Cell growth occurs when the overall rate of cellular biosynthesis (production of biomolecules or anabolism) is greater than ...

or cell proliferation. Some cytokines, such as Fas ligand, are used as "death" signals; they cause target cells to undergo programmed

cell death Cell death is the event of a biological cell ceasing to carry out its functions. This may be the result of the natural process of old cells dying and being replaced by new ones, as in programmed cell death, or may result from factors such as d ...

or ''

apoptosis Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes incl ...

''. The nerve growth factor (NGF) was first discovered by

Rita Levi-Montalcini Rita Levi-Montalcini (, ; 22 April 1909 – 30 December 2012) was an Italian Nobel laureate, honored for her work in neurobiology. She was awarded the 1986 Nobel Prize in Physiology or Medicine jointly with colleague Stanley Cohen for th ...

, which won her a

Nobel Prize in Physiology or Medicine The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accord ...

List of classes

Individual growth factor proteins tend to occur as members of larger families of structurally and

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

arily related proteins. There are many families, some of which are listed below: *

Adrenomedullin Adrenomedullin (ADM or AM) is a vasodilator peptide hormone of uncertain significance in human health and disease. It was initially isolated in 1993 from a pheochromocytoma, a tumor of the adrenal medulla: hence the name. In humans ADM is encoded ...

(AM) * Angiopoietin (Ang) * Autocrine motility factor * Bone morphogenetic proteins (BMPs) * Ciliary neurotrophic factor family **

Ciliary neurotrophic factor Ciliary neurotrophic factor is a protein that in humans is encoded by the ''CNTF'' gene. The protein encoded by this gene is a polypeptide hormone and neurotrophic factor whose actions have mainly been studied in the nervous system where it p ...

(CNTF) **

Leukemia inhibitory factor Leukemia inhibitory factor, or LIF, is an interleukin 6 class cytokine that affects cell growth by inhibiting differentiation. When LIF levels drop, the cells differentiate. Function LIF derives its name from its ability to induce the terminal ...

(LIF) **

Interleukin-6 Interleukin 6 (IL-6) is an interleukin that acts as both a pro-inflammatory cytokine and an anti-inflammatory myokine. In humans, it is encoded by the ''IL6'' gene. In addition, osteoblasts secrete IL-6 to stimulate osteoclast formation. Smoo ...

(IL-6) *

Colony-stimulating factor Colony-stimulating factors (CSFs) are secreted glycoproteins that bind to receptor proteins on the surfaces of hemopoietic stem cells, thereby activating intracellular signaling pathways that can cause the cells to proliferate and differentia ...

s **

Macrophage colony-stimulating factor The colony stimulating factor 1 (CSF1), also known as macrophage colony-stimulating factor (M-CSF), is a secreted cytokine which causes hematopoietic stem cells to differentiate into macrophages or other related cell types. Eukaryotic cells also ...

(M-CSF) **

Granulocyte colony-stimulating factor Granulocyte colony-stimulating factor (G-CSF or GCSF), also known as colony-stimulating factor 3 (CSF 3), is a glycoprotein that stimulates the bone marrow to produce granulocytes and stem cells and release them into the bloodstream. Functiona ...

(G-CSF) **

Granulocyte macrophage colony-stimulating factor Granulocyte-macrophage colony-stimulating factor (GM-CSF), also known as colony-stimulating factor 2 (CSF2), is a monomeric glycoprotein secreted by macrophages, T cells, mast cells, natural killer cells, endothelial cells and fibroblasts th ...

(GM-CSF) * Epidermal growth factor (EGF) *

Ephrin Ephrins (also known as ephrin ligands or Eph family receptor interacting proteins) are a family of proteins that serve as the ligands of the Eph receptor. Eph receptors in turn compose the largest known subfamily of receptor protein-tyrosine kinas ...

s **

Ephrin A1 Ephrin A1 is a protein that in humans is encoded by the ''EFNA1'' gene. This gene encodes a member of the ephrin (EPH) family. The ephrins and EPH-related receptors comprise the largest subfamily of receptor protein-tyrosine kinases and have bee ...

Ephrin A2 Ephrin-A2 is a protein that in humans is encoded by the ''EFNA2'' gene. This gene encodes a member of the ephrin Ephrins (also known as ephrin ligands or Eph family receptor interacting proteins) are a family of proteins that serve as the ligan ...

Ephrin A3 Ephrin A3 is a protein that in humans is encoded by the ''EFNA3'' gene. This gene encodes a member of the ephrin (EPH) family. The ephrins and EPH-related receptors comprise the largest subfamily of receptor protein-tyrosine kinases and have be ...

Ephrin A4 Ephrin A4 is a protein that in humans is encoded by the ''EFNA4'' gene. This gene encodes a member of the ephrin (EPH) family. The ephrins and EPH-related receptors comprise the largest subfamily of receptor protein-tyrosine kinases and have been ...

Ephrin A5 Ephrin A5 is a protein that in humans is encoded by the ''EFNA5'' gene. Ephrin A5 is a glycosylphosphatidylinositol (GPI)-anchored protein of the ephrin-A subclass of ephrin ligands that binds to the EphA subclass of Eph receptors. Eph ...

Ephrin B1 Ephrin B1 is a protein that in humans is encoded by the ''EFNB1'' gene. It is a member of the ephrin family. The encoded protein is a type I membrane protein and a ligand of Eph-related receptor tyrosine kinases. It may play a role in cell adhes ...

Ephrin B2 Ephrin-B2 is a protein that in humans is encoded by the ''EFNB2'' gene. Function This gene encodes a member of the ephrin (EPH) family. The ephrins and EPH-related receptors comprise the largest subfamily of receptor protein-tyrosine kinases a ...

** Ephrin B3 *

Erythropoietin Erythropoietin (; EPO), also known as erythropoetin, haematopoietin, or haemopoietin, is a glycoprotein cytokine secreted mainly by the kidneys in response to cellular hypoxia; it stimulates red blood cell production (erythropoiesis) in the bo ...

(EPO) *

Fibroblast growth factor Fibroblast growth factors (FGF) are a family of cell signalling proteins produced by macrophages; they are involved in a wide variety of processes, most notably as crucial elements for normal development in animal cells. Any irregularities in their ...

GDNF family of ligands The GDNF family of ligands (GFL) consists of four neurotrophic factors: glial cell line-derived neurotrophic factor (GDNF), neurturin (NRTN), artemin (ARTN), and persephin (PSPN). GFLs have been shown to play a role in a number of biological proce ...

Glial cell line-derived neurotrophic factor Glial cell line-derived neurotrophic factor (GDNF) is a protein that, in humans, is encoded by the ''GDNF'' gene. GDNF is a small protein that potently promotes the survival of many types of neurons. It signals through GFRα receptors, particula ...

(GDNF) **

Neurturin Neurturin (NRTN) is a protein that is encoded in humans by the ''NRTN'' gene. Neurturin belongs to the glial cell line-derived neurotrophic factor (GDNF) family of neurotrophic factors, which regulate the survival and function of neurons. Neur ...

** Persephin **

Artemin Artemin, also known as enovin or neublastin, is a protein that in humans is encoded by the ''ARTN'' gene. Function Artemin is a neurotrophic factor in the glial cell line-derived neurotrophic factor family of ligands which are a group of lig ...

* Growth differentiation factor-9 (GDF9) *

Hepatocyte growth factor Hepatocyte growth factor (HGF) or scatter factor (SF) is a paracrine cellular growth, motility and morphogenic factor. It is secreted by mesenchymal cells and targets and acts primarily upon epithelial cells and endothelial cells, but also acts on ...

(HGF) * Hepatoma-derived growth factor (HDGF) *

Insulin Insulin (, from Latin ''insula'', 'island') is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the ''INS'' gene. It is considered to be the main anabolic hormone of the body. It regulates the metabolism o ...

Insulin-like growth factor The insulin-like growth factors (IGFs) are proteins with high sequence similarity to insulin. IGFs are part of a complex system that cells use to communicate with their physiologic environment. This complex system (often referred to as the IGF "a ...

s **

Insulin-like growth factor-1 Insulin-like growth factor 1 (IGF-1), also called somatomedin C, is a hormone similar in tertiary structure, molecular structure to insulin which plays an important role in childhood growth, and has Anabolism, anabolic effects in adults. IGF-1 ...

(IGF-1) ** Insulin-like growth factor-2 (IGF-2) *Interleukins ** IL-1- Cofactor for IL-3 and IL-6. Activates T cells. **

IL-2 The Ilyushin Il-2 (Russian: Илью́шин Ил-2) is a ground-attack plane that was produced by the Soviet Union in large numbers during the Second World War. The word ''shturmovík'' ( Cyrillic: штурмовик), the generic Russian term ...

– T-cell growth factor. Stimulates IL-1 synthesis. Activates B-cells and NK cells. ** IL-3 – Stimulates production of all non-lymphoid cells. ** IL-4 – Growth factor for activated B cells, resting T cells, and mast cells. ** IL-5 – Induces differentiation of activated B cells and eosinophils. ** IL-6 – Stimulates Ig synthesis. Growth factor for plasma cells. ** IL-7 – Growth factor for pre-B cells. * Keratinocyte growth factor (KGF) * Migration-stimulating factor (MSF) * Macrophage-stimulating protein (MSP), also known as hepatocyte growth factor-like protein (HGFLP) *

Myostatin Myostatin (also known as growth differentiation factor 8, abbreviated GDF8) is a protein that in humans is encoded by the ''MSTN'' gene. Myostatin is a myokine that is produced and released by myocytes and acts on muscle cells to inhibit muscle ...

(GDF-8) *

Neuregulin Neuregulins or neuroregulins are a family of four structurally related proteins that are part of the EGF family of proteins. These proteins have been shown to have diverse functions in the development of the nervous system and play multiple essen ...

s **

Neuregulin 1 Neuregulin 1, or NRG1, is a gene of the epidermal growth factor family that in humans is encoded by the ''NRG1'' gene. NRG1 is one of four proteins in the neuregulin family that act on the EGFR family of receptors. Neuregulin 1 is produced in n ...

(NRG1) **

Neuregulin 2 Neuregulin 2, also known as NRG2, is a protein which in humans is encoded by the ''NRG2'' gene. Function Neuregulin 2 (NRG2) is a novel member of the neuregulin family of growth and differentiation factors. Through interaction with the ErbB ...

(NRG2) **

Neuregulin 3 Neuregulin 3, also known as NRG3, is a neural-enriched member of the neuregulin protein family which in humans is encoded by the ''NRG3'' gene. The NRGs are a group of signaling proteins part of the superfamily of epidermal growth factor, EGF ...

(NRG3) **

Neuregulin 4 Neuregulin 4 also known as NRG4 is a member of the neuregulin protein family which in humans is encoded by the ''NRG4'' gene. Function The neuregulins, including NRG4, activate erb-b2 receptor tyrosine kinase 4 (ERBB4) to initiating cell signal ...

(NRG4) *

Neurotrophins Neurotrophins are a family of proteins that induce the survival, development, and function of neurons. They belong to a class of growth factors, secreted proteins that can signal particular cells to survive, differentiate, or grow. Growth facto ...

Brain-derived neurotrophic factor Brain-derived neurotrophic factor (BDNF), or abrineurin, is a protein found in the and the periphery. that, in humans, is encoded by the ''BDNF'' gene. BDNF is a member of the neurotrophin family of growth factors, which are related to the cano ...

(BDNF) ** Nerve growth factor (NGF) **

Neurotrophin-3 Neurotrophin-3 is a protein that in humans is encoded by the ''NTF3'' gene. The protein encoded by this gene, NT-3, is a neurotrophic factor in the NGF (Nerve Growth Factor) family of neurotrophins. It is a protein growth factor which has activi ...

(NT-3) **

Neurotrophin-4 Neurotrophin-4 (NT-4), also known as neurotrophin-5 (NT-5), is a protein that in humans is encoded by the ''NTF4'' gene. It is a neurotrophic factor that signals predominantly through the TrkB receptor tyrosine kinase Receptor tyrosine kina ...

(NT-4) *

Placental growth factor Placental growth factor (PlGF) is a protein that in humans is encoded by the ''PGF'' gene. Placental growth factor (PGF) is a member of the VEGF (vascular endothelial growth factor) sub-family - a key molecule in angiogenesis and vasculogenesis, ...

(PGF) *

Platelet-derived growth factor Platelet-derived growth factor (PDGF) is one among numerous growth factors that regulate cell growth and division. In particular, PDGF plays a significant role in blood vessel formation, the growth of blood vessels from already-existing blood v ...

(PDGF) *

Renalase Renalase, FAD-dependent amine oxidase is an enzyme that in humans is encoded by the RNLS gene. Renalase is a flavin adenine dinucleotide-dependent amine oxidase that is secreted into the blood from the kidney. Structure Gene The gene encodi ...

(RNLS) – Anti-apoptotic survival factor * T-cell growth factor (TCGF) *

Thrombopoietin Thrombopoietin (THPO) also known as megakaryocyte growth and development factor (MGDF) is a protein that in humans is encoded by the ''THPO'' gene. Thrombopoietin is a glycoprotein hormone produced by the liver and kidney which regulates the pro ...

(TPO) *

Transforming growth factor Transforming growth factor (, or TGF) is used to describe two classes of polypeptide growth factors, TGFα and TGFβ. The name "Transforming Growth Factor" is somewhat arbitrary, since the two classes of TGFs are not structurally or genetically ...

s ** Transforming growth factor alpha (TGF-α) **

Transforming growth factor beta Transforming growth factor beta (TGF-β) is a multifunctional cytokine belonging to the transforming growth factor superfamily that includes three different mammalian isoforms (TGF-β 1 to 3, HGNC symbols TGFB1, TGFB2, TGFB3) and many other ...

(TGF-β) *

Tumor necrosis factor-alpha Tumor necrosis factor (TNF, cachexin, or cachectin; formerly known as tumor necrosis factor alpha or TNF-α) is an adipokine and a cytokine. TNF is a member of the TNF superfamily, which consists of various transmembrane proteins with a homolog ...

(TNF-α) *

Vascular endothelial growth factor Vascular endothelial growth factor (VEGF, ), originally known as vascular permeability factor (VPF), is a signal protein produced by many cells that stimulates the formation of blood vessels. To be specific, VEGF is a sub-family of growth factors, ...

(VEGF) *

Wnt Signaling Pathway The Wnt signaling pathways are a group of signal transduction pathways which begin with proteins that pass signals into a cell through cell surface receptors. The name Wnt is a portmanteau created from the names Wingless and Int-1. Wnt signaling p ...

In platelets

The

alpha granules Alpha granules, (α-granules) also known as platelet alpha-granules are a cellular component of platelets. Platelets contain different types of Granule (cell biology), granules that perform different functions, and include alpha granules, dense gra ...

in blood

platelets Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby ini ...

contain growth factors PDGF, IGF-1, EGF, and TGF-β which begin healing of wounds by attracting and activating

macrophages Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer ce ...

fibroblast A fibroblast is a type of cell (biology), biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework (Stroma (tissue), stroma) for animal Tissue (biology), tissues, and plays a critical role in wound ...

s, and

endothelial cell The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel ...

Uses in medicine

For the last two decades, growth factors have been increasingly used in the treatment of

hematologic Hematology ( always spelled haematology in British English) is the branch of medicine concerned with the study of the cause, prognosis, treatment, and prevention of diseases related to blood. It involves treating diseases that affect the produc ...

and oncologic diseases and cardiovascular diseases such as: *

neutropenia Neutropenia is an abnormally low concentration of neutrophils (a type of white blood cell) in the blood. Neutrophils make up the majority of circulating white blood cells and serve as the primary defense against infections by destroying bacteria ...

myelodysplastic syndrome A myelodysplastic syndrome (MDS) is one of a group of cancers in which immature blood cells in the bone marrow do not mature, and as a result, do not develop into healthy blood cells. Early on, no symptoms typically are seen. Later, symptoms may ...

(MDS) *

leukemia Leukemia ( also spelled leukaemia and pronounced ) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells. These blood cells are not fully developed and are called ''blasts'' or ' ...

s *

aplastic anaemia Aplastic anemia is a cancer in which the body fails to make blood cells in sufficient numbers. Blood cells are produced in the bone marrow by stem cells that reside there. Aplastic anemia causes a deficiency of all blood cell types: red blood c ...

transplantation *

for cardiovascular diseases

References

External links

*
FGF5 in Hair Tonic Products

FGF1 in Cosmetic Products
{{Authority control * Immune system

Comparison to cytokines

List of classes

In platelets

Uses in medicine

See also

References

External links