4354
Using dissociated hippocampal neuronal cultures , we identified a critical and cell autonomous role for the receptor tyrosine kinase EphA4 in mediating activity - induced homeostatic down - regulation of excitatory synaptic strength .
 Chemical: tyrosine
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: tyrosine