7040
We conclude that activation of the MEK /ERK signaling pathway is necessary for TPA -induced mononuclear cell differentiation .
 protein: MEK
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: MEK 
Answer:
 protein: MEK