tokens: First , from different cell lines three or all four of the nuclear proteins were specifically cross-linked by UV irradiation to the radioactively labeled TRE -DNA fragment .
folded_tokens: first , from different cell lines three or all four of the nuclear proteins were specifically cross-linked by uv irradiation to the radioactively labeled tre -dna fragment .
labels: O O O O O O O O O O O O B-protein_family_or_group I-protein_family_or_group O O O O B-other_name I-other_name O O O O B-DNA_domain_or_region O O O