1536
Levels of c-fos and c-jun transcripts remained elevated during periods of PKC activation and also returned to levels observed in control cells by 30-36 days, when the cells entered retrodifferentiation .
 protein: PKC
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: PKC