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Thus, IL-2 -induced IL-2R alpha promoter activity requires a complex upstream element , which appears to contain binding sites for both positive and negative regulatory factors .
 IL-2R alpha promoter, binding sites, IL-2, complex upstream element
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:
 IL-2R alpha promoter, binding sites, IL-2, complex upstream element