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Using mice lacking neurofibromin 1 ( Nf1 ) in type II collagen - expressing cells , ( Nf1col2 ( - / - ) mutant mice ) , we then show that lack of neurofibromin in post - mitotic chondrocytes triggers a number of phenotypes reminiscent of the ones observed in mice characterized by FGFR gain - of - function mutations .
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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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