11851
However, in differentiating erythroid cells , which must incorporate high levels of iron to sustain hemoglobin synthesis , and in macrophages , which are involved in iron storage, transcriptional regulation seemed to be a relevant mechanism.
 hemoglobin, macrophages, differentiating erythroid cells
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:
 hemoglobin, macrophages, differentiating erythroid cells