A total of 27 combinations of different promoters and enhancers were tested by transfection into cultured cells .
a total of 27 combinations of different promoters and enhancers were tested by transfection into cultured cells .
O O O O O O O B-DNA_family_or_group O B-DNA_family_or_group O O O B-other_name O B-cell_line I-cell_line O