The intracellular location and kinetics at which the simian virus 40 T antigen and the cellular protein p53 associate with one another were determined for simian virus 40-transformed mouse (215) and rat (14B) cells. Cells were labeled under pulse-chase conditions and fractionated into nuclear and cytoplasmic components, and the proteins were immunoprecipitated with monoclonal antibodies (pAb 41...

A simian virus 40 (SV40) T-antigen mutant containing only the N-terminal 136 amino acids, able to bind to Rb and p300 but not p53, partially inhibited p53-mediated transcription without affecting the ability of p53 to bind DNA. These results suggest that SV40 T antigen can regulate p53-mediated transcription either directly through protein-protein association or indirectly through interaction w...

The simian virus 40 (SV40) large tumor (T) antigen is sufficient to transform cells in cultures and induce tumors in experimental animals. Transformation of primary cells in cultures requires both overcoming growth arrest by stimulating the cell cycle and blocking cell death activities presumably activated by oncogene-mediated hyperproliferation signals. The study presented here examined the ab...

AIMS Although the aetiology of medulloblastoma remains elusive, several lines of evidence suggest an association with the human neurotropic polyomavirus JC and its oncoprotein T antigen. The tumour forming properties of JC virus T antigen are the result, at least in part, of its ability to bind and inactivate tumour suppressor/cell cycle regulatory proteins, such as p53 and the retinoblastoma f...

The p53 protein was first described 10 years ago in studies from three independent laboratories (Linzer and Levine, 1979; Lane and Crawford, 1979; DeLeo et a/., 1979). p53 was shown to form oligomeric protein complexes with the SV40 large tumor antigen (T antigen) in SV40-infected or -transformed cells (Linzer and Levine, 1979; Lane and Crawford, 1979). That the p53 protein was not encoded by S...

OBJECTIVE To investigate the biological behavior of classical and atypical osteoblastomas in comparison to osteosarcomas. METHODS Based on histological parameters, 30 osteoblastomas were subclassified as classical osteoblastomas (23/30) or atypical osteoblastoma (high cellularity, prominent blue osteoid, and epithelioid osteoblasts--7/30). Comparative immunohistochemical and clinical analysis...

introduction: leukoplakia is the most common precancerous lesion of the oral mucosa and may range microscopically form benign hyperkeratosis to invasive squamous cell carcinoma. p53 is a tumor suppressor protein; whereas, proliferative cell nuclear antigen (pcna) is a proliferative marker. the aim of this study was to evaluate the immunohistochemical expressions of p53 and pcna in oral leukopla...

p53-plus-ras-transformed rat cell lines express a tumor-specific transplantation antigen that is common to a number (85%) of independently derived p53-plus-ras-transformed cell lines. This has been shown by immunizing rats with irradiated p53-plus-ras-transformed cells and demonstrating protection of these animals by subsequent live-cell tumor challenge. Several c-myc-plus-ras-transformed cell ...

Activation of the ARF-p53 tumor suppressor pathway is one of the cell's major defense mechanisms against cancer induced by oncogenes. The ARF-p53 pathway is dysfunctional in a high proportion of human cancers. The regulation of the ARF-p53 signaling pathway has not yet been well characterized. In this study polyoma virus (Py) is used as a tool to better define the ARF-p53 signaling pathway. Py ...

background : basal cell carcinoma is the most common form of skin cancer in men. increased marker expressions of apoptosis and cell proliferation have been found in the majority of basal cell carcinomas. our purpose was to determine whether any correlation between immunohistochemical expressions of p53 and ki-67 in different histopathological variants of basal cell carcinoma and patient’s age, ...