tokens: The main activity of the silencer has been mapped to the first 900 bp of 5' flanking DNA , which contains nine binding sites for a nuclear factor present in non- erythroid cells but not in erythroid cells .
folded_tokens: the main activity of the silencer has been mapped to the first 900 bp of 5' flanking dna , which contains nine binding sites for a nuclear factor present in non- erythroid cells but not in erythroid cells .
labels: O O O O O B-DNA_family_or_group O 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 O O O O B-protein_family_or_group I-protein_family_or_group O O O B-cell_type I-cell_type O O O B-cell_type I-cell_type O