4355
Reducing the endogenous level of EphA4 in individual neurons by RNAi effectively blocked activity - induced scaling - down of excitatory synaptic strength , while co - transfection of RNAi resistant EphA4 rescued this effect .
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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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