Early increase in nuclear acidic protein synthesis after SV40 infection

WHEN the replication of density-inhibited cultures of fibroblasts1,2 is stimulated by a change of medium3–5, the rate of nuclear acidic protein synthesis10–13 is immediately increased. We wanted to determine whether the induction of cellular DNA synthesis by an oncogenic virus6–9 is also preceded by nuclear acidic protein synthesis. We report here the effect of SV40 virus infection of a permissive and a non-permissive cell line on their synthesis of total cellular proteins and nuclear acidic proteins in the first hours after infection.