3317
In the erythroleukemia cell line K562 , due to the absence of Spi-B , only PU.1 bound to the Btk promoter .
 ( protein: Btk, None) , ( protein: PU.1, None) , ( protein: Spi-B, None) , ( DNA: Btk promoter, None) , ( cell line: erythroleukemia cell line K562, 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: Btk, None) , ( protein: PU.1, None) , ( protein: Spi-B, None) , ( DNA: Btk promoter, None) , ( cell line: erythroleukemia cell line K562, None) 