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The two proteins differ by a 14-amino acid serine-rich insertion present in one of the CREB isoforms .
 protein: CREB isoforms; protein: 14-amino acid serine-rich insertion; protein: CREB
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:
 protein: CREB isoforms; protein: 14-amino acid serine-rich insertion; protein: CREB