There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Resting cultures of nonpermissive rat 3Y1 cells were infected with simian and T antigen
expression and entry into S phase were examined under various conditions of culture.
In the complete absence of serum from the medium or at an extremely high cell density,
the cells delayed T antigen expression and entry into S phase, leaving the interval
between the two events constant. Results using the viral mutants deleted in the coding
region for the small t antigen ruled out the role of this antigen in induction of
S phase. From these and other results presented, we conclude that the large T antigen
induces S phase with the same efficiency under different conditions of cultures. We
also present the evidence that the large T antigen function is required and is sufficient
for entry into S phase in the second as well as in the first generation.