Number of Simultaneously Expressed Enzyme Alterations Correlates with Progression of N‐Ethyl‐N‐hydroxyethylnitrosamine‐induced Hepatocarcinogenesis in Rats

Abstract Preneoplastic and neoplastic liver cell lesions, induced by EHEN (N‐ethyl‐N‐hydroxyethylnitrosamine) in rats, were investigated to establish the numbers of simultaneously expressed altered enzyme phenotypes within the lesion cells. The lesions were divided into 5 classes on the basis of altered expression in one or more of the following 5 enzymes: glutathione S‐transferase placental form, glucose‐6‐phosphate dehydrogenase, glucose‐6‐phosphatase, adenosine triphosphatase, and γ‐glutamyl transpeptidase. Class 1 lesions contained cells expressing one altered enzyme. Similarly, class 2, 3, 4 and 5 lesions