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Here we describe the isolation and expression of a cDNA encoding PTF beta , as well as functional studies using anti- PTF beta antibodies .
 ( protein: PTF beta, None) , ( protein: anti- PTF beta antibodies, None) , ( protein: PTF beta, None) , ( DNA: cDNA, 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: PTF beta, None) , ( protein: anti- PTF beta antibodies, None) , ( protein: PTF beta, None) , ( DNA: cDNA, None) 