G protein oncogenes in pituitary tumors.
G proteins are involved in the transduction of external signals from cell surface receptors to intracellular effectors. Somatic mutations activating the a-subunit of G(s) (the stimulatory regulatory protein of adenylyl cyclase) by inhibiting its intrinsic GTPase activity have been first identified in human GH-secreting adenomas and subsequently found in thyroid tumors and in McCune-Albright syndrome. It has been therefore proposed that the gene encoding the GS a-subunit may be converted into an oncogene (gsp for GS protein) in cell types that proliferate in response to cAMP. Since several G proteins mediate signaling pathways that are effective in coupling external stimuli to cell proliferation, it appears most likely that in the near future other G protein oncogenes will be identified in human tumors.
Spada
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Institute of Endocrine Sciences, Maggiore Hospital IRCCS, Milan, Italy.
Vallar
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Faglia
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