2080
We recently confirmed the existence of gelatinase granules as a subpopulation of peroxidase-negative granules by double-labeling immunogold electron microscopy on intact cells and by subcellular fractionation .
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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:
 None