6888
We show herein that Rnf4 , an E3 ubiquitin ligase that targets SUMO - modified proteins , accumulates in DSB repair foci and is required for both homologous recombination ( HR ) and non - homologous end joining repair .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
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