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The expression level of endogenous M2 mRNA in HeLa cells was detected using RNase protection assay 4 h following Trail ( 250 mug / ml ) treatment .
 Anatomy: HeLa cells
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Anatomy 
Text: {0} 
Answer:
 Anatomy: HeLa cells