11668
However, the NF-kappaB activation pathway involving the acidic sphingomyelinase of the endolysosomial membrane did not seem to participate in the LPS -induced NF-kappaB activation in U937 cells .
 ( protein: NF-kappaB, None) , ( protein: acidic sphingomyelinase, None) , ( cell line: U937 cells, None) , ( protein: NF-kappaB, 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: NF-kappaB, None) , ( protein: acidic sphingomyelinase, None) , ( cell line: U937 cells, None) , ( protein: NF-kappaB, None) 