66466
B7 is a type of peripheral membrane protein found on activated antigen presenting cell s ( APC ) that , when paired with either a CD28 or CD152 ( CTLA-4 ) surface protein on a T cell , can produce a costimulatory signal to enhance or decrease the activity of a MHC - TCR signal between the APC and the T cell , respectively .
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Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities:  
Answer:
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