8541
Although Fas upregulation is central to the preservation of immunologic tolerance, little is known about the molecular machinery underlying this process.
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
 Entities:  
Answer:
 None