Molecule Menu

DNA, Deoxyribonucleic acid (DNA)
The molecule that carries the genetic information of a cell. DNA is composed of two strands of nucleotides that twist around each other to make the shape of a double helix.

DNA polymerase
An enzyme that is used to replicate deoxyribonucleic acid (DNA) molecules.

EGF, Epidermal growth factor (EGF)
A protein that stimulates cell growth and proliferation. EGF was originally isolated from assays that stimulate epithelial cell growth; EGF does work as a growth promoter on other cell types as well.


EGF receptor, Epidermal growth factor (EGF) receptor
A membrane-spanning protein that binds to EGF and activates the cell growth and proliferation pathway. Her-2 is a specific example of an EGF receptor.

Estrogen
A hormone that is necessary for cell growth and proliferation in breast cells.

Estrogen receptor
A protein that binds estrogen in the blood and carries it into breast cells. The complex then activates cell growth and proliferation in the nucleus.

Fos
A protein that interacts with the Jun protein to form AP-1, a transcription factor. When active, Fos and Jun bind together via a stretch of leucine amino acids that mesh like teeth in a zipper. The other ends of the proteins bind DNA to begin the transcription of growth-promoting genes. Researchers speculate that mutations in Fos and Jun may make them bind abnormally, activating target genes without responding to the usual controls. Fos is also present at high levels in cancers such as colon cancer.

GDP, Guanosine diphosphate (GDP)
A small molecule essential to the regulation of signaling pathways in living cells. GDP is formed when a phosphate group is removed from guanosine triphosphate (GTP). Some signal proteins, such as Ras, are active when bound to GTP, and inactive when bound to GDP.

Gleevec
A small molecule being used to treat chronic myeloid leukemia. Gleevec was designed to bind to the mutant protein BCR-ABL thus blocking the signal for the overproliferation of white blood cells.

Grb2, Growth factor receptor-bound protein 2 (Grb2)
A protein that acts as adaptor molecule between a growth factor receptor and other signaling proteins. In a key signaling pathway, Grb2 binds an active PDGF receptor and activates a guanine-nucleotide exchange factor for the Ras protein.

Growth factors
Proteins that stimulate cell division, proliferation or differentiation. See EGF and PDGF.

GTP
description:'A small molecule essential to the regulation of signaling pathways in living cells. When a phosphate group is removed, GTP is converted to guanosine diphosphate (GDP). Some signal proteins, such as Ras, are active when bound to GTP, and inactive when bound to GDP.',
lnglabel: 'Guanosine triphosphate (GTP)'

Jun
A protein that interacts with the Fos protein to form AP-1, a transcription factor. When active, Fos and Jun bind together via a stretch of leucine amino acids that mesh like teeth in a zipper. The other ends of the proteins bind DNA to begin the transcription of growth-promoting genes. Researchers speculate that mutations in Fos and Jun may make them bind abnormally, activating target genes without responding to the usual controls.

MAP kinases, Mitogen-activated protein (MAP) kinases
These enzymes \u2013 sometimes known as extracellular signal-regulated kinases (ERKs) \u2013 add phosphates to other proteins to activate or deactivate them. Mutations in these kinases can disrupt cell signaling and cause abnormal cell growth and proliferation. These proteins are good targets for drugs against cancer.

Myc
description:'A transcription factor that activates growth \u2013 promoting genes and repressing the expression of genes that can arrest growth. In cancers such as Burkitt lymphoma, chromosomal rearrangements can make many copies of the myc gene or remove the usual constraints on its expression.

p53
A protein that acts as a \"checkpoint\" in cells, inducing either growth arrest, DNA repair, or cell death when the cell\'s DNA is damaged. Mutations can occur in many places in the p53 gene (and thus the p53 protein). Cells with mutated p53 tend to be genetically unstable. Most cancer cells have mutations in the p53 protein.

PDGF, Platelet derived growth factor (PDGF)
PDGF stimulates growth and division in cells such as fibroblasts and smooth muscle cells. PDGF is important in tissue repair, activating cells of the immune system and synthesizing components of the extracellular matrix. Some cancer cells produce their own PDGF, which releases them from their dependency on growth signals from other cells.

PDGF receptor, Platelet derived growth factor (PDGF) receptor
PDGF receptors are large membrane-spanning proteins with an extracellular and an intracellular component. Two PDGF receptor proteins "dimerize" to bind a single platelet-derived growth factor. The cytoplasmic portion has kinase activity \u2013 able to add phosphate molecules to other molecules to activate them. This receptor can contribute to cancer if rendered active for an extended period of time.

Raf
A protein that interacts with the Ras protein. Raf is an example of a kinase enzyme, able to activate other proteins by adding phosphate molecules to serine and threonine amino acids. Mutations in the Raf protein are present in a large percentage of human malignant melanomas.

Ras
A protein loosely associated with the inner surface of the cell membrane. The Ras protein binds guanine nucleotides \u2013 guanosine diphosphate (GDP) and guanosine triphosphate (GTP). When a stimulatory signal arrives, Ras releases its GDP and acquires a GTP molecule, entering an active state and emitting a signal to another protein. After transmitting the signal, Ras deactivates itself, by cleaving a phosphate molecule from the GTP to reduce it to GDP, or another protein called Ras-GAP comes in to break the GTP down. A single amino acid change can alter the function of Ras, causing it to bind GTP but making it unable to deactivate. Ras mutations are prevalent in many human cancers, including colon, skin, and lung.

Ras-GAP, Ras GTPase activating protein (GAP)
A regulator of the Ras protein\'s signaling activity. Ras-GAP stimulates Ras\'s own weak ability to reduce bound guanosine triphosphate (GTP) to guanosine-diphosphate (GDP), thereby rendering itself inactive. See Ras.

Ras-GEF, Ras guanine exchange factor (GEF)
description:'Activates the Ras protein by exchanging a bound guanosine diphosphate (GDP) for guanosine triphosphate (GTP).

Ribosome
description:'A structure made up of proteins and RNA that is the site of protein production in the cell. Ribosomes decode messenger RNA (mRNA) and assemble amino acids into proteins based on the mRNA script.

RNA, Ribonucleic acid (RNA)
A molecule similar to DNA. RNA is usually single-stranded and instead of thymine has uracil as one of its four nitrogenous bases. Different types of RNA molecules are used for different purposes. For example, messenger RNA carries the information to make a protein from the nucleus to a ribosome, while transfer RNA delivers amino acids to a ribosome during protein production.

RNA polymerase
An enzyme that makes a ribonucleic acid (RNA) copy of a gene during the process of transcription.',

Src

Tamoxifen
A small molecule that binds to the estrogen receptor and thus blocks the binding of the hormone estrogen to the estrogen receptor. Tamoxifen is used as a drug treatment for breast cancer because estrogen binding is necessary for the growth and proliferation of many breast cancer cells.

Thymine
One of the four nitrogenous bases in deoxyribonucleic acid (DNA). Ultraviolet radiation can cause neighboring thymines to combine or "dimerize," leading to cancer if the DNA damage is not repaired.

VEGF
Vascular endothelial growth factor (VEGF)

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Inside Cancer - Multimedia Guide to Cancer Biology, Hallmarks of cancer, Molecule map, Growing uncontrollably, Evading death, Processing nutrients, Becoming immortal, Invading tissues, Avoiding detection, Promoting mutations, Causes and prevention, Smoking, Inheritance, Diet, Mold, Viruses, Sunlight,Diagnosis and treatment, Pathology, Pharmacogenetics, Targeted therapies, Pathways to cancer, At the cell surface, Beneath the membrane, A bevy of interactions, To the nucleus, Inside the nucleus, Making the protein, Releasing the protein.

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