421
The presence of multiple CREB isoforms with identical DNA-binding specificities but differences in the presumed regulatory domain raises the possibility that CREB proteins may be able to integrate distinct regulatory signals at the level of gene transcription .
 protein: regulatory domain; protein: CREB; protein: CREB isoforms; protein: CREB proteins; 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: regulatory domain; protein: CREB; protein: CREB isoforms; protein: CREB proteins; protein: CREB