7242
CD4+ and CD8+ T cells differ in their beta-binding profiles , which may explain the more pronounced down-regulation of CD28 in senescent CD8+ T cells .
 ( protein: CD28, None) , ( cell type: CD8+ T cells, None) , ( cell type: CD8+ T cells, 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: CD28, None) , ( cell type: CD8+ T cells, None) , ( cell type: CD8+ T cells, None) 