In the tumor microenvironment (TME; pathological activation) in vivo, stimulation with tumor-derived factors (TDFs), such as vascular endothelial growth factor (VEGF) and granulocyte-macrophage colony-stimulating factors (GM-CSFs) induces MDSC differentiation in bone marrow (BM) from hemopoietic progenitor cells (HPCs) through common myeloid progenitors (CMPs) and granulocyte-macrophage progenitors (GMPs). Here, CSF2 is linked to neoplasm.