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We previously reported the purification of human PTF , a complex of four subunits , and the molecular cloning and characterization of PTF gamma and delta subunits .
 protein: human PTF; protein: four subunits
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: human PTF, four subunits 
Answer:
 protein: human PTF; protein: four subunits