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However, during infection by EBV , ligation of CD2 caused thymocytes to proliferate in the absence of exogenous cytokines .
 cell type: thymocytes; protein: CD2; protein: exogenous cytokines
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: thymocytes, CD2, exogenous cytokines 
Answer:
 cell type: thymocytes; protein: CD2; protein: exogenous cytokines