8921
When we analyzed the nature of STAT proteins capable of binding to IL-2Ralpha , pim-1 , and IRF-1 GAS elements after cytokine stimulation , we observed IFN-alpha -induced binding of STAT1 , STAT3 , and STAT4 , but not STAT5 to all of these elements.
 STAT3, IL-2Ralpha, STAT5, STAT1, STAT4, STAT proteins, cytokine, IFN-alpha
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:
 STAT3, IL-2Ralpha, STAT5, STAT1, STAT4, STAT proteins, cytokine, IFN-alpha