8095
These repressor sites are pyrimidine rich and bind avidly to the polypyrimidine tract binding protein ( PTB ) in HeLa nuclear extracts as determined by UV crosslinking / competition assays .
 polypyrimidine tract binding protein, PTB
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 polypyrimidine tract binding protein, PTB