Immunocytochemical demonstration of a phenobarbital-inducible cytochrome P450 in putative preneoplastic foci of rat liver.

Putative preneoplastic foci of rat liver, so far believed to be deficient in monooxygenases, are shown to contain a cytochrome P450 isoenzyme inducible by phenobarbital. The isoenzyme is also present and appears catalytically active in liver tumors obtained after promotion with phenobarbital and alpha-hexachlorocyclohexane.