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This enhancement was eliminated if a conserved 20-bp sequence was removed from the intron or if a dominant-negative ets-binding factor was co-transfected with the reporter gene .
 intron, dominant-negative ets-binding factor, reporter gene, conserved 20-bp sequence
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 intron, dominant-negative ets-binding factor, reporter gene, conserved 20-bp sequence