1506
In monocytes , the nuclear factor NF-kappa B has been invoked as an important transcription factor in the expression of cytokine genes , of cell-surface receptors and in the expression of human immunodeficiency virus .
 nuclear factor NF-kappa B, monocytes, cytokine genes, NF-kappa B, transcription factor, cell-surface receptors
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:
 nuclear factor NF-kappa B, monocytes, cytokine genes, NF-kappa B, transcription factor, cell-surface receptors