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In order to characterize the function of cis-acting elements , we have developed an in vitro system in which a DRA promoter construct is transcribed more efficiently in extracts from B cells than in extracts from class II-negative HeLa cells .
 cell type: B cells; DNA: cis-acting elements; cell line: class II-negative HeLa cells; DNA: DRA promoter construct
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: B cells; DNA: cis-acting elements; cell line: class II-negative HeLa cells; DNA: DRA promoter construct