14615
Although the assay involves the dramatic loss of red cell production , it should be possible to define important regulatory domains that can then be assayed using less stringent systems, such as cell-free extracts for in vitro transcription .
 None
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:
 None