2939
Mice lacking IL - 6 displayed a two - fold lower expression of the lipocalin - 2 gene ( lcn2 ) , and this difference was confirmed by real - time reverse transcriptase - polymerase chain reaction .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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