19287
Insulin - like growth factor - 1 ( IGF - 1 ) is a neurotrophic factor and plays an important role in promoting axonal growth from dorsal root ganglion ( DRG ) neurons .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None