27
Thus, the novel enhancer element identified in this study is probably a target site for both positive and negative factors .
 protein: positive and negative factors; protein: negative factors; protein: positive
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:
 protein: positive and negative factors; protein: negative factors; protein: positive