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This led to the hypothesis that some of the Rel/ NF-kappa B proteins were key nuclear factors in functions of accessory cells of the immune response .
 NF-kappa B, Rel/ NF-kappa B proteins, accessory cells, nuclear factors
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:
 NF-kappa B, Rel/ NF-kappa B proteins, accessory cells, nuclear factors