KITLG and neoplasm: Substantial research concluded that, MDSCs are recruited and activated by tumor-derived cytokines and growth factors, such as interleukin (IL)-2, IL-6, IL-1b, stem cell factor (SCF), granulocyte monocyte colony stimulating factor (GM-CSF), G-CSF, and vascular endothelial growth factor (VEGF) (Lim et al., 2020).