2430
In hematopoietic system, RA and RARs , predominantly RAR alpha may play key roles for the proliferation and differentiation of hematopoietic progenitors .
 ( protein: RAR alpha, None) , ( cell type: hematopoietic progenitors, None) , ( protein: RARs, 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: RAR alpha, None) , ( cell type: hematopoietic progenitors, None) , ( protein: RARs, None) 