12859
In vivo probe studies have shown that the activity of several hepatic cytochrome P450 enzymes , such as CYP2D6 and CYP3A4 , is increased during pregnancy , whereas the activity of others , such as CYP1A2 , is decreased .
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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:
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