17740
We also describe here the docking of the PCU - derived compounds into a homology model of the sigma - 1 ( sigma 1 ) receptor , which was developed to gain insight into binding of these cage compounds to the receptor .
 Chemical: PCU
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: PCU