2233
However , the extent of narrowing of the airway lumen due to ASM shortening can be influenced by many factors and it remains a real challenge to decipher the exact role of ASM in causing asthmatic symptoms .
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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:
 None