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We previously identified and analyzed a 45-nucleotide sequence ( downstream regulatory element 1 [ DRE 1 ]), +195 to +240 , at the boundary of the R/U5 region of the long terminal repeat which is required for HTLV-I basal transcription .
 R/U5 region, 45-nucleotide sequence, long terminal repeat, downstream regulatory element 1, +195 to +240, DRE 1
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:
 R/U5 region, 45-nucleotide sequence, long terminal repeat, downstream regulatory element 1, +195 to +240, DRE 1