11665
The transduction pathway leading to NF-kappaB activation in U937 cells involved the intracellular generation of reactive oxygen species ( ROS) , as demonstrated by the concomitant inhibitory effects of antioxidants on NF-kappaB activation and the emission of a fluorescent probe reacting intracellularly with hydrogen peroxide .
 U937 cells, NF-kappaB, NF-kappaB
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:
 U937 cells, NF-kappaB, NF-kappaB