180
These studies demonstrate that a single cytokine can activate different combinations of Stat proteins under different physiological conditions , and also indicate two mechanisms by which distinct cytokines can activate the same Stat protein .
 cytokine, cytokines, Stat protein, Stat proteins
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:
 cytokine, cytokines, Stat protein, Stat proteins