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Since the identification of LRP5 as the causative gene for the osteoporosis pseudoglioma syndrome ( OPPG ) as well as the high bone mass ( HBM ) phenotype , LRP5 and the Wnt / beta - catenin signaling have been extensively studied for their role in the differentiation and proliferation of osteoblasts , in the apoptosis of osteoblasts and osteocytes and in the response of bone to mechanical loading .
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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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