7038
Treatment of cells with PD98059 , a specific inhibitor of mitogen-activated protein kinase kinase ( MEK ), inhibited TPA -induced ERK2 activity.
 mitogen-activated protein kinase kinase, ERK2, MEK
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 mitogen-activated protein kinase kinase, ERK2, MEK