In the presence of M-CSF alone, the M-MDSCs from all three tissues significantly gained F4/80 expression (Fig. 4), with tumor and spleen M-MDSCs having the highest ability with a 54.6 and 62.7% conversion rate, respectively, compared with BM (40% conversion), although these differences were not statistically different (Fig. 4B). Here, CSF1 is linked to neoplasm.