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Therefore, we examined the RB status of a series of B-cell mutants that are defective in class II expression, generated either in vitro or derived from Bare Lymphocyte Syndrome (BLS) patients.
 protein: RB
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
 Entities: RB 
Answer:
 protein: RB