5577
Previous reports have identified a role for the tyrosine kinase receptor EphB4 and its ligand , ephrinB2 , as potential mediators of both bone formation by osteoblasts and bone resorption by osteoclasts .
 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