25925
Prostaglandin E2 acts via bone marrow macrophages to block PTH - stimulated osteoblast differentiation in vitro .
 Chemical: Prostaglandin E2
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: Prostaglandin E2