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To investigate the activity of a single transcription factor in individual viable cells , we have applied an assay that uses the fluorescence-activated cell sorter to quantitate beta-galactosidase ( beta-gal ).
 cell type: individual viable cells; protein: beta-gal; protein: transcription factor; protein: beta-galactosidase
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 cell type: individual viable cells; protein: beta-gal; protein: transcription factor; protein: beta-galactosidase