5099
We show here that AM580 , a stable retinobenzoic derivative originally synthesized as a RAR alpha agonist , is a powerful inducer of granulocytic maturation in NB4 , an APL -derived cell line , and in freshly isolated APL blasts .
 NB4, RAR alpha, freshly isolated APL blasts, APL -derived cell line
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:
 NB4, RAR alpha, freshly isolated APL blasts, APL -derived cell line