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Previous protein-DNA binding studies have shown that HS-40 consists of multiple nuclear factor binding motifs that are occupied in vivo in an erythroid lineage- and developmental stage- specific manner .
 HS-40, nuclear factor binding motifs
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:
 HS-40, nuclear factor binding motifs