Evidence for Threshold Effects in Transformation of Pancreatic β Cells by SV40 T Antigen in Transgenic Mice
Transgenic mice harboring hybrid insulin-T antigen genes manifest heritable patterns of tumor formation (Hanahan 1985; Efrat and Hanahan 1987; Adams et al. 1987; Teitelman et al. 1988). In all mice inheriting the hybrid oncogene, denoted RIP1-Tag, its cell-specific expression in ß cells in all the pancreatic islets of Langerhans causes ß-cell transformation and proliferation, which results in islet hyperplasia. This is followed by development of only a few islets into solid, vascularized tumors and consequent premature death. It thus appears that T antigen is necessary but not sufficient for tumor formation and that additional events may be required.
KeywordsHybrid Gene Enhancer Element Insulin Gene Insulin Promoter Young Adult Mouse
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