| transforming growth factor | <growth factor> Proteins secreted by transformed cells that can stimulate growth of normal cells. Unfortunate misnomer, since they induce aspects of transformed phenotype, such as growth in semi solid agar, but do not actually transform. Transforming growth factor alpha, 50 amino acid polypeptide originally isolated from viral transformed rodent cells, contains EGF like domain and binds to EGF receptor. Stimulates growth of microvascular endothelial cells, i.e. Is angiogenic. Transforming growth factor beta a homodimer of two 112 chains, polypeptide is secreted by many different cell types, stimulates wound healing but in vitro is also a growth inhibitor for certain cell types. The transforming growth factor family includes many of the bone morphogenetic proteins. Acronym: TGF (18 Nov 1997) |
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| transforming growth factor alpha | Factor isolated in a variety of tissues including epithelium, and maternal decidua. It is closely related to epidermal growth factor (epidermal growth factor-urogasterone) and binds to the egf receptor. Tgf-alpha acts synergistically with tgf-beta in inducing phenotypic transformation, but its physiological role is unknown. (12 Dec 1998) |
| transforming growth factor beta | Factor synthesised in a wide variety of tissues including platelets, placenta, and both normal and transformed cell lines. It acts synergistically with tgf-alpha in inducing phenotypic transformation and can also act as a negative autocrine growth factor. Tgf-beta also has a potential role in embryonal development, cellular differentiation, hormone secretion, and immune function. There are at least three forms of tgf-beta: tgf-beta1, tgf-beta2, and tgf-beta1.2. The latter is a heterodimer made up of both tgf-beta1 and tgf-beta2. (12 Dec 1998) |
| transforming growth factors | <chemical> Hormonally active polypeptides that can induce the transformed phenotype when added to normal, non-transformed cells. They have been found in culture fluids from retrovirally transformed cells and in tumour-derived cells as well as in non-neoplastic sources. Their transforming activities are due to the simultaneous action of two otherwise unrelated factors, transforming growth factor alpha and transforming growth factor beta. Chemical name: Animal growth regulators, transforming growth factors (12 Dec 1998) |
| transforming oncogene | <molecular biology> A gene that upon transfection converts a previously immortalised cell to the malignant phenotype. (09 Oct 1997) |
| transforming virus | <molecular biology, virology> Viruses capable of inducing malignant transformation of animal cells in culture. Among the Oncovirinae, nondefective viruses that lack oncogenes can induce tumours such as leukaemias in animals, but cannot transform in vitro. On acquisition of oncogenes they become (acute) transforming viruses. (18 Nov 1997) |
| transformism | <biology> The hypothesis, or doctrine, that living beings have originated by the modification of some other previously existing forms of living matter; opposed to abiogenesis. Origin: F. Transformisme. Source: Websters Dictionary (01 Mar 1998) |