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ISG15 mRNA accumulation in U937 cells is not detectable before 6 h of IFN-alpha treatment , peaks at 24 h, and requires protein synthesis .
 RNA: ISG15 mRNA; protein: IFN-alpha; cell line: U937 cells
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 RNA: ISG15 mRNA; protein: IFN-alpha; cell line: U937 cells