22387
To determine whether these enhancers are also necessary for the maintenance of transcriptional activity , we conditionally deleted E3 ' in mature B cells that possessed Ed ( - / - ) alleles .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None