science

Growth factor

Growth factor is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Growth factor rather than just read about it. In short: A growth factor is a naturally occurring substance capable of stimulating cell proliferation, wound healing, and occasionally cellular differentiation. Usually it is a secreted protein or a steroid hormone.

Key takeaways

Growth factor belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Growth factor to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Growth factor from memory before moving on to harder problems.

Reference excerpt

A growth factor is a naturally occurring substance capable of stimulating cell proliferation, wound healing, and occasionally cellular differentiation. Usually it is a secreted protein or a steroid hormone.

Comparison to cytokines Growth factor is sometimes used interchangeably among scientists with the term cytokine. Historically, cytokines were associated with hematopoietic (blood and lymph forming) cells and immune system cells (e.g., lymphocytes and tissue cells from spleen, thymus, and lymph nodes). For the circulatory system and bone marrow 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 molecules. 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 and 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

Individual growth factor proteins tend to occur as members of larger families of structurally and evolutionarily related proteins. There are many families, some of which are listed below:

Adrenomedullin (AM) Angiopoietin (Ang) Autocrine motility factor Bone morphogenetic proteins (BMPs) Ciliary neurotrophic factor family Colony-stimulating factors Epidermal growth factor (EGF) Ephrin Fibroblast growth factor (FGF) 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 factors Interleukins Keratinocyte growth factor (KGF) Migration-stimulating factor (MSF) Macrophage-stimulating protein (MSP), also known as hepatocyte growth factor-like protein (HGFLP) Myostatin (GDF-8) Neuregulins Neurotrophins Placental growth factor (PGF) Platelet-derived growth factor (PDGF) Transforming growth factors Vascular endothelial growth factor (VEGF)

In platelets The alpha granules in blood platelets contain growth factors PDGF, IGF-1, EGF, and TGF-β which begin healing of wounds by attracting and activating macrophages, fibroblasts, and endothelial cells.

Uses in medicine For the last two decades, growth factors have been increasingly used in the treatment of hematologic and oncologic diseases and cardiovascular diseases such as:

skin wound healing and regeneration of other tissues such as bone (PDGF-BB) neutropenia myelodysplastic syndrome (MDS) leukemias 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 Wound healing § Overview of involved growth factors

References

External links Growth+Factors at the U.S. National Library of Medicine Medical Subject Headings (MeSH) FGF5 in Hair Tonic Products FGF1 in Cosmetic Products

Worked examples

Example 1 — a first encounter with Growth factor

Start with the simplest possible case. Write down what Growth factor claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Growth factor before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Growth factor ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Growth factor

In research: Growth factor appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Growth factor in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Growth factor is common in secondary-school and first-year university syllabi. It links to neighbouring topics Growth factors, Immune system, so understanding it makes those chapters shorter.
In everyday life: Look for Growth factor outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Growth factor in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Growth factor means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Growth factor out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Growth factor in simple terms?

Why does Growth factor matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Growth factor?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Growth factor.