2302
In an effort to better understand the biology of this tumor additional immunohistochemical studies for the protein product of p53 tumor suppressor gene and estrogen receptor expression by tumor cells , as well as the type of immune cells infiltrating the tumor were performed.
 ( protein: protein product, None) , ( protein: estrogen receptor, None) , ( cell type: tumor cells, None) , ( cell type: immune cells, None) , ( DNA: p53 tumor suppressor gene, 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: protein product, None) , ( protein: estrogen receptor, None) , ( cell type: tumor cells, None) , ( cell type: immune cells, None) , ( DNA: p53 tumor suppressor gene, None) 