tokens: We show that a central core in the kappa E3' enhancer is active at the pre-B-cell stage but is repressed by flanking negative-acting elements .
folded_tokens: we show that a central core in the kappa e3' enhancer is active at the pre-b-cell stage but is repressed by flanking negative-acting elements .
labels: O O O O O O O O B-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region O O O O B-other_name I-other_name O O O O B-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region O