1573
The predicted protein sequence of B1 is 81% identical to human matrix metalloproteinase 9 ( MMP9 ), demonstrating that it is the bovine homologue of this enzyme.
 MMP9, B1, matrix metalloproteinase 9
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:
 MMP9, B1, matrix metalloproteinase 9