Two CAGGTG E-boxes , located at the 5'- and 3'- ends of the silencer , were necessary for this silencer activity .
two caggtg e-boxes , located at the 5'- and 3'- ends of the silencer , were necessary for this silencer activity .
O B-DNA_substructure I-DNA_substructure O O O O O O O O O O O O O O O O B-other_name I-other_name O