4013
From these results, we can conclude that electrostatic interactions of retinoids with the RAR alpha -LBD play a significant role in ligand binding .
 RAR alpha, RAR alpha -LBD
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 RAR alpha, RAR alpha -LBD