[Cytochrome P-450 in tumors and during carcinogenesis]

The current data concerning regulation of cytochrome P-450 isoforms in tumours and during carcinogenesis are reviewed. These findings can be summarized as follows: (i) the total level of cytochrome P-450 in tumours is generally decreased in comparison with homologous normal tissues; (ii) this decrease is observed during both the transformation and progression of the tumour; (iii) individual isoforms of cytochrome P-450 in tumours and pretumour cell clones are expressed in different ways and can thus be regarded as markers for identifying various stages of carcinogenesis.