10138
When transcriptionally active, the human immunodeficiency virus ( HIV ) promoter contains a nucleosome-free region encompassing both the promoter /enhancer region and a large region ( 255 nucleotides [nt]) downstream of the transcription start site .
 promoter /enhancer region, 255 nucleotides, transcription start site, promoter, promoter
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:
 promoter /enhancer region, 255 nucleotides, transcription start site, promoter, promoter