16857
Ataxia Telangiectasia Mutated ( ATM ) kinase , a central regulator of the DNA damage response , regulates the activity of several E3 - ubiquitin ligases , and the ubiquitination - proteasome system is a consistent target of ATM .
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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:
 None