12878
Recent studies reveal that a family of transcription factors , signal transducers and activators of transcription ( STATs ) directly mediate many cytokine signals .
 signal transducers and activators of transcription, cytokine, transcription factors, STATs
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:
 signal transducers and activators of transcription, cytokine, transcription factors, STATs