868
Tyrosine phosphorylation of cellular proteins is the earliest identifiable event following T - cell antigen receptor ( TCR ) stimulation and is essential for activating downstream signaling machinery .
 GENE: T - cell antigen receptor; GENE: TCR
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
 Entities: T - cell antigen receptor, TCR 
Answer:
 GENE: T - cell antigen receptor; GENE: TCR