6790
A p21 peptide spanning amino acids 139 - 164 was found to bind PCNA in a filter binding assay and this peptide suppressed recombinant p21 - PCNA interaction .
 p21 peptide, PCNA, p21, PCNA
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 p21 peptide, PCNA, p21, PCNA