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In this study, a CD40 -dependent B cell culture system was used to examine the role of different signal transduction elements .
 protein: CD40; DNA: signal transduction elements
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: CD40, signal transduction elements 
Answer:
 protein: CD40; DNA: signal transduction elements