3052
Sequence analysis revealed that PB1 is composed of adjacent binding sites for Ets and AP-1 transcription factors .
 PB1, adjacent binding sites, Ets, AP-1, transcription factors
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:
 PB1, adjacent binding sites, Ets, AP-1, transcription factors