15153
At the same time , the conjugates have comparable and rather low cytostatic activity for 38C13 cells , which are used as a negative control , in vitro .
 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