10207
A 1-kb region of the gene that includes 5' flanking sequence was reported earlier to contain functional promoter activity and was specifically demethylated in expressing cells in contrast to null cells .
 expressing cells, null cells, 5' flanking sequence, 1-kb region
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:
 expressing cells, null cells, 5' flanking sequence, 1-kb region