tokens: We have cloned and sequenced a portion of the ER upstream regulatory region from the ER -positive MCF-7 and the ER -negative MDA-MB-231 breast cancer cell lines to determine if sequence alterations in this region account for the ER -negative phenotype of some tumors .
folded_tokens: we have cloned and sequenced a portion of the er upstream regulatory region from the er -positive mcf-7 and the er -negative mda-mb-231 breast cancer cell lines to determine if sequence alterations in this region account for the er -negative phenotype of some tumors .
labels: O O O O O O O O O B-protein_molecule B-DNA_domain_or_region I-DNA_domain_or_region I-DNA_domain_or_region O O B-protein_molecule O O O O B-protein_molecule O O B-body_part O O O O O O B-other_name I-other_name O O O O O O B-protein_molecule O O O O O O