12056
Interactions between the checkpoint abrogator UCN - 01 and several pharmacological inhibitors of the mitogen - activated protein kinase ( MAPK ) kinase ( MEK ) / MAPK pathway have been examined in a variety of human leukemia cell lines .
 mitogen - activated protein kinase ( MAPK ) kinase, MEK, MAPK
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 mitogen - activated protein kinase ( MAPK ) kinase, MEK, MAPK