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The increase in IL-2 gene expression triggered by CD28 involves a kappa B-like sequence in the 5'-regulatory region of the IL-2 promoter , called CD28 -responsive element .
 IL-2 promoter, kappa B-like sequence, CD28, CD28 -responsive element, IL-2, IL-2, CD28, 5'-regulatory 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:
 IL-2 promoter, kappa B-like sequence, CD28, CD28 -responsive element, IL-2, IL-2, CD28, 5'-regulatory region