tokens: To test the validity of the hypothesis that hypomethylation of DNA plays an important role in the initiation of carcinogenic process , 5-azacytidine ( 5-AzC )( 10 mg / kg ), an inhibitor of DNA methylation , was given to rats during the phase of repair synthesis induced by the three carcinogens , benzo[a]-pyrene ( 200 mg / kg ), N-methyl-N-nitrosourea ( 60 mg / kg ) and 1,2-dimethylhydrazine ( 1,2-DMH )( 100 mg / kg ). The initiated hepatocytes in the liver were assayed as the gamma - glutamyltransferase ( gamma - GT ) positive foci formed following a 2 - week selection regimen consisting of dietary 0 .