9001
Serine phosphorylation of STAT1 and STAT3 was seen occasionally in other leukemias , but it was a universal finding only in CLL .
 ( protein: STAT3, None) , ( protein: STAT1, 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: STAT3, None) , ( protein: STAT1, None) 