in two revertant cell lines of k562/adm , amplification of the mdr1 gene was maintained at the same level as in k562/adm , but expression of the 4.5-kilobase mdr1 mrna was greatly decreased , indicating that amplified genes may be inactivated at the level of transcription without a corresponding loss of amplified dna .
C1515670
expression
C0040649
transcription