14121
In addition, this proliferative parameter maintained its prognostic significance when the patients were stratified according to lymph node involvement , menopausal status , and nuclear estrogen receptor content .
 ( protein: nuclear estrogen receptor, 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: nuclear estrogen receptor, None) 