tokens: To determine whether vanadate could inhibit PEPCK gene transcription , a series of chimeric genes containing several deletions in the P - enolypyruvate carboxykinase promoter between - 550 and - 68 was linked to the structural genes for either amino - 3 - glycosyl phosphotransferase ( neo ) or chloramphenicol acetyltransferase and introduced into hepatoma cells using three methods : ( a ) infection with a Moloney murine leukemia virus - based retrovirus , ( b ) transfection and stable selection for neo expression , or ( c ) transient expression of chloroamphenicol acetyltransferase .