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The role of the human immunodeficiency virus ( HIV-1 ) Nef protein in T cell activation pathways was investigated using a Jurkat CD4 + cell line stably transfected with a Nef expression vector .
 Jurkat CD4 + cell line, human immunodeficiency virus ( HIV-1 ) Nef protein, Nef protein, CD4
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:
 Jurkat CD4 + cell line, human immunodeficiency virus ( HIV-1 ) Nef protein, Nef protein, CD4