590
Expression studies on TCF-1 protein have been hampered by the difficulty to raise antibodies due to extreme evolutionary conservation.
 ( protein: TCF-1, None) , ( protein: TCF-1 protein, None) , ( protein: antibodies, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( protein: TCF-1, None) , ( protein: TCF-1 protein, None) , ( protein: antibodies, None) 