View source for Growth factor

{{short description|Protein or other substance that stimulates cellular proliferation}}
{{redirect|Growth factors|the journal|Growth Factors (journal)}}
{{more citations needed|date=February 2014}}
{{Use dmy dates|date=July 2020}}

A '''growth factor''' is a naturally occurring substance capable of stimulating [[cell proliferation]], [[wound healing]], and occasionally [[cellular differentiation]].<ref>{{DorlandsDict|three/000038554|growth factor}}</ref> Usually it is a secreted [[protein]] or a [[steroid hormone]]. 

{{anchor|cytokine}}

== Comparison to cytokines ==
''Growth factor'' is sometimes used interchangeably among scientists with the term ''[[cytokine]].''<ref name="YorioClark2007">{{cite book | first1 = Thomas | last1 = Yorio | first2 = Abbot F. | last2 = Clark | first3 = Martin B. | last3 = Wax | name-list-style = vanc |title=Ocular Therapeutics: Eye on New Discoveries|url=https://books.google.com/books?id=7jVNuIt8vm4C&pg=PA88|year=2007|publisher=Academic Press|isbn=978-0-12-370585-3|page=88}}</ref> Historically, cytokines were associated with [[hematopoietic]] (blood and lymph forming) cells and [[immune system]] cells (e.g., [[lymphocyte]]s and tissue cells from [[spleen]], [[thymus]], and [[lymph node]]s). For the [[circulatory system]] and [[bone marrow]] in which cells can occur in a liquid suspension and not bound up in solid [[tissue (biology)|tissue]], it makes sense for them to communicate by soluble, circulating protein [[molecule]]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 [[Granulocyte colony-stimulating factor|G-CSF]] and [[Granulocyte macrophage colony-stimulating factor|GM-CSF]], others have an inhibitory effect on [[cell growth]] or cell proliferation. Some cytokines, such as [[Fas ligand]], are used as "death" signals; they cause target cells to undergo programmed [[cell death]] or ''[[apoptosis]]''.

== List of classes ==
{{Incomplete list|date=February 2011}}
{{no references|section|date=August 2025}}
Individual growth factor proteins tend to occur as members of larger families of structurally and [[evolution]]arily related proteins.  There are many families, some of which are listed below:
* [[Adrenomedullin]] (AM)
* [[Angiopoietin]] (Ang)
* [[Autocrine motility factor]]
* [[Bone morphogenetic protein]]s (BMPs)
* Ciliary neurotrophic factor family
* [[Colony-stimulating factor]]s
* [[Epidermal growth factor]] (EGF)
* [[Ephrin]]s
* [[Erythropoietin]] (EPO)
* [[Fibroblast growth factor]] (FGF)
* [[Bovine somatotropin|Foetal Bovine Somatotrophin]] (FBS)
* [[GDNF family of ligands]]
* [[Growth differentiation factor-9]] (GDF9)
* [[Hepatocyte growth factor]] (HGF)
* [[Hepatoma-derived growth factor]] (HDGF)
* [[Insulin]]
* [[Insulin-like growth factor]]s
*Interleukins
* [[Keratinocyte growth factor]] (KGF)
* [[PRG4|Migration-stimulating factor]] (MSF)
* [[Macrophage-stimulating protein]] (MSP), also known as hepatocyte growth factor-like protein (HGFLP)
* [[Myostatin]] (GDF-8)
* [[Neuregulin]]s
* [[Neurotrophins]]
* [[Placental growth factor]] (PGF)
* [[Platelet-derived growth factor]] (PDGF)
* [[Renalase]] (RNLS) – Anti-apoptotic survival factor
* [[T-cell growth factor]] (TCGF)
* [[Thrombopoietin]] (TPO)
* [[Transforming growth factor]]s
* [[Tumor necrosis factor-alpha]] (TNF-α)
* [[Vascular endothelial growth factor]] (VEGF)

== In platelets ==
The [[alpha granule]]s in blood [[platelet]]s contain growth factors PDGF, IGF-1, EGF, and TGF-β which begin healing of wounds by attracting and activating [[macrophage]]s, [[fibroblast]]s, and [[endothelial cell]]s.

== Uses in medicine ==
For the last two decades, growth factors have been increasingly used in the treatment of [[hematology|hematologic]] and [[oncology|oncologic]] diseases<ref>{{cite journal | vauthors = Cottler-Fox M, Klein HG | title = Transfusion support of hematology and oncology patients. The role of recombinant hematopoietic growth factors | journal = Archives of Pathology & Laboratory Medicine | volume = 118 | issue = 4 | pages = 417–20 | date = April 1994 | pmid = 7909429 }}</ref><ref>{{cite journal | vauthors = Aaronson SA | title = Growth factors and cancer | journal = Science | volume = 254 | issue = 5035 | pages = 1146–53 | date = November 1991 | pmid = 1659742 | doi = 10.1126/science.1659742 | bibcode = 1991Sci...254.1146A }}</ref> and cardiovascular diseases<ref>{{cite journal | vauthors = Domouzoglou EM, Naka KK, Vlahos AP, Papafaklis MI, Michalis LK, Tsatsoulis A, Maratos-Flier E | title = Fibroblast growth factors in cardiovascular disease: The emerging role of FGF21 | journal = American Journal of Physiology. Heart and Circulatory Physiology | volume = 309 | issue = 6 | pages = H1029-38 | date = September 2015 | pmid = 26232236 | pmc = 4747916 | doi = 10.1152/ajpheart.00527.2015 }}</ref><ref>{{Cite journal|last1=Gorenoi|first1=Vitali|last2=Brehm|first2=Michael U.|last3=Koch|first3=Armin|last4=Hagen|first4=Anja|date=2017|title=Growth factors for angiogenesis in peripheral arterial disease|journal=The Cochrane Database of Systematic Reviews|volume=2017|issue=6 |article-number=CD011741|doi=10.1002/14651858.CD011741.pub2|issn=1469-493X|pmid=28594443|pmc=6481523}}</ref> such as:

* [[skin wound healing and regeneration of other tissues such as bone]] (PDGF-BB)
* [[neutropenia]]
* [[myelodysplastic syndrome]] (MDS)
* [[leukemia]]s
* [[aplastic anaemia]]
* [[bone marrow]] transplantation
* [[angiogenesis]] for cardiovascular diseases

== See also ==
* [[Angiogenesis]]
* [[Bone growth factor]]
* [[Cytokine]]
* [[Growth factor receptor]]
* [[Human Genome Organisation]]
* [[Mitogen]]
* [[Neurotrophic factor]]
* [[Receptor (biochemistry)]]
* [[Signal transduction]]
* {{slink|Wound healing|Overview of involved growth factors}}

== References ==
{{reflist}}

== External links ==
* {{MeshName|Growth+Factors}}
* [https://web.archive.org/web/20170223153745/https://www.evolisproducts.com.au/fgf-5-hair-loss/ FGF5 in Hair Tonic Products]
* [https://web.archive.org/web/20100208230857/http://www.esheeesthetic.com/technology.php FGF1 in Cosmetic Products]

{{Signaling proteins}}
{{Cytokines}}
{{Wound healing}}
{{Growth factor receptor modulators}}

{{Authority control}}

[[Category:Growth factors|*]]
[[Category:Immune system]]