21066
To investigate the presence of DNA modifications in these cells , we isolated ALDH - positive lung cells from A / J mice exposed to the lung carcinogen 4 - ( methylnitrosamino ) - 1 - ( 3 - pyridyl ) - 1 - butanone .
 Chemical: 4 - ( methylnitrosamino ) - 1 - ( 3 - pyridyl ) - 1 - butanone
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: 4 - ( methylnitrosamino ) - 1 - ( 3 - pyridyl ) - 1 - butanone