5417
We further confirmed by site - directed mutagenesis and mass spectrometry that Ser - 7 is a site for PKC - stimulated phosphorylation in heterologously expressed rat and human DATs .
 Chemical: Ser
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: Ser