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The identification of a tissue-specific deoxyribonuclease I hypersensitive site approximately 3kb upstream of the transcription start site led to the characterization of a cell type-specific enhancer region .
 deoxyribonuclease I, transcription start site, cell type-specific enhancer, cell type-specific enhancer region, deoxyribonuclease I hypersensitive site, 3kb upstream
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:
 deoxyribonuclease I, transcription start site, cell type-specific enhancer, cell type-specific enhancer region, deoxyribonuclease I hypersensitive site, 3kb upstream