9813
Messenger RNA ( mRNA ) levels for the granulocyte-colony stimulating factor ( G-CSF ) receptor , granulocyte-macrophage (GM)-CSF receptor alpha subunit and tumor necrosis factor (TNF) receptors I (p55) and II (p75) were also detected in this subset in addition to c-kit and flt-3 , receptors known to be expressed on progenitor cells .
 mRNA, flt-3, granulocyte-colony stimulating factor ( G-CSF ) receptor, progenitor cells, granulocyte-colony stimulating factor, G-CSF, granulocyte-macrophage (GM)-CSF receptor alpha subunit, c-kit, Messenger RNA
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:
 mRNA, flt-3, granulocyte-colony stimulating factor ( G-CSF ) receptor, progenitor cells, granulocyte-colony stimulating factor, G-CSF, granulocyte-macrophage (GM)-CSF receptor alpha subunit, c-kit, Messenger RNA