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The human T-cell leukemia virus type 1 posttranscriptional trans-activator Rex contains a nuclear export signal .
 protein: nuclear export signal; protein: Rex; protein: human T-cell leukemia virus type 1 posttranscriptional trans-activator
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: nuclear export signal, Rex, human T-cell leukemia virus type 1 posttranscriptional trans-activator 
Answer:
 protein: nuclear export signal; protein: Rex; protein: human T-cell leukemia virus type 1 posttranscriptional trans-activator