1299
Previous work of ours has demonstrated that a significant amount of natural killer (NK) activity variance after surgery in stage I and II breast cancer patients could be accounted for by both the estrogen receptor ( ER ) status of the tumor and by social factors , namely, perceived social support and seeking social support as a general coping strategy .
 protein: ER; protein: estrogen receptor
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: ER; protein: estrogen receptor