5085
The RAR-RXR as well as the RXR-RXR pathway is involved in signaling growth inhibition of human CD34+ erythroid progenitor cells .
 RXR-RXR, human CD34+ erythroid progenitor cells, RAR-RXR
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:
 RXR-RXR, human CD34+ erythroid progenitor cells, RAR-RXR