tokens: cDNA clones for the human erythroid ALAS isozyme were isolated from a fetal liver library .
folded_tokens: cdna clones for the human erythroid alas isozyme were isolated from a fetal liver library .
labels: B-DNA_domain_or_region I-DNA_domain_or_region O O B-protein_family_or_group I-protein_family_or_group I-protein_family_or_group I-protein_family_or_group O O O O B-tissue I-tissue O O