12328
These findings provide new important information on the role of the ERK pathway in the regulation of epigenetic marks and gene expression that may concur to regulate in vivo the cellular changes underlying the onset of the opioid withdrawal syndrome .
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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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