15471
The most recently characterized receptor , the C5a 2 receptor ( previously known as C5L2 or GPR77 ) , has been regarded as a passive binding protein , but signaling activities are now ascribed to it , so we propose that it be formally identified as a receptor and be given a name to reflect this .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
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