1641
This element had maximal activity in lymphoid cells , paralleling the cell type specificity of Elf-1 expression .
 Elf-1, lymphoid 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:
 Elf-1, lymphoid cells