T Antigens of SV40-transformed Cells

Two characteristics of cells transformed by the papovavirus SV40 are an increased cell-proliferation rate and the ability to cause tumors when infected into animals. Because these two phenomena are of fundamental importance in both biology and medicine, much effort is being concentrated on understanding how a relatively simple virus like SV40 is able to bring about such profound effects. Virally transformed cells contain viral DNA integrated into their chromosomes, they express viral RNA transcripts, and they contain viral proteins (for review, see Kelly and Nathans 1977). It is likely that at least some of the events occurring upon transformation are mediated by the viral proteins. However, before we can hope to understand the function of these viral proteins, we need a clear description of the various species present in transformed cells and of their interaction with hostcell components. Recent work has shown that in productively infected cells the early region...