5417
The use of specific antibodies allowed the identification of at least RAR beta in some of the DNA - protein complexes , although the four sequences bind single RARs transfected in COS cells much less efficiently , or not at all , when compared to a canonical RAR responsive element .
 RAR beta, RARs, RAR responsive element
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 RAR beta, RARs, RAR responsive element