12517
Experiments in COS-1 and EL-4 cells confirmed both hypotheses and revealed that the second factor activated by Tpl-2 is NF-kappaB .
 EL-4 cells, COS-1, NF-kappaB, Tpl-2
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:
 EL-4 cells, COS-1, NF-kappaB, Tpl-2