STAT3 and neoplasm: Furthermore, tumor releases GM-CSF and IL-6 promotes the conversion of myeloid cells to an MDSC phenotype, mainly through the activation of a CCAA T-enhancer-binding protein β(C/EBP β)-mediated program that implicates the downstream blockade of STAT3 for terminal differentiation (Marigo et al., 2010; Zhang et al., 2010).