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The best - studied neurotrophin , nerve growth factor ( NGF ) , is a major survival factor in sympathetic and sensory neurons and promotes differentiation in a well - studied model system , PC12 cells .
 GENE: nerve growth factor; GENE: NGF
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 GENE: nerve growth factor; GENE: NGF