19308
Epigenetic changes are involved in the switching ' on ' and ' off ' of many genes , and it has been suggested that the DNA hypermethylation of specific gene promoters , histone modifications ( acetylation , phosphorylation , and methylation ) and small interfering or micro RNAs be regarded epigenetic gene targets for the regulation of disease - associated cellular changes .
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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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