Granulocyte macrophage colony-stimulating factor (GM-CSF) secreted by glioma cells also activates STAT5 signaling in myeloid derived suppressor cells (MDSCs) to induce Bcl2a1 expression and downregulate IRF8 transcription, thereby inhibiting apoptosis and promoting proliferation, respectively [22,23]. Here, STAT5B is linked to glioma.