tokens: Since 1988 , several families of functionally important T cell transcription factors have been identified .
folded_tokens: since 1988 , several families of functionally important t cell transcription factors have been identified .
labels: O O O O O O 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