1436
We previously showed that heterozygous mice with an R740S mutation in the a3 subunit of V - ATPase ( + / R740S ) have mild osteopetrosis resulting from an ~ 90 % reduction in proton translocation across osteoclast membranes .
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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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