12091
Its activity is essential for the generation of B cell but not of T cell precursors , although the differentiation of the latter is not normal.
 cell type: T cell precursors; cell type: B cell
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: T cell precursors, B cell 
Answer:
 cell type: T cell precursors; cell type: B cell