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The negative-acting sequences repress enhancer activity in a position- and orientation-independent manner at the pre-B-cell stage .
 DNA: negative-acting sequences
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:
 DNA: negative-acting sequences