5867
Signaling by tyrosine kinases involves direct associations between proteins with Src homology 2 ( SH2 ) domains and sites of tyrosine phosphorylation .
 tyrosine kinases, Src homology 2, SH2
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 tyrosine kinases, Src homology 2, SH2