Abstract
The growth of preneoplastic nodules during the feeding of a carcinogenic 2-acetylaminofluorene (2-AAF) regimen is preceded by several alterations in the physiologic homeostasis. Many of these alterations can be considered adaptive responses to the drug exposure. One property of AAF could be identified that clearly distinguishes this complete rat liver carcinogen from at least two other, incomplete rat liver carcinogens. Highly specific redox cycling in mitochondria was demonstrated in vitro, and this observation could well contribute an explanation of the morphologic and histochemical observations in vivo. It is emphasized that nongenotoxic effects may play an important role in the generation of tumors by genotoxic carcinogens.