Loss of Two-Stage-Control of Cell Proliferation in Rat Liver After a Single Dose of the Carcinogen Diethylnitrosamine

Stimulation of liver cell proliferation in adolescent rats by endogenous stimuli or by xenobiotic compounds such as phenobarbital, α-hexachlorocyclohexane (α-HCH) etc. is controlled by a Two-Stage mechanism: After initiation of the replicative process by the growth stimulus (first signal) a second signal is required which is provided by consumption of protein-containing food. In the absence of dietary protein cells programmed for replication are arrested some hours before commencement of DNA synthesis [R. Schulte Hermann, Cancer Res. 37, 166 (1977)].