1566
In contrast, addition of either ligand or antagonist in combination with a heat activation step promoted DNA binding by approximately 3-fold over that of heat-activated unliganded receptors .
 protein: unliganded receptors
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: unliganded receptors