EGFR and neoplasm: MDSCs increase the expression of tumor PD-L1 expression via the activation of EGFR/MAPK signaling pathway and result in CD8+ T cell exhaustion and T regulatory cell expansion [58,60], thus abrogation of tumor-derived GM-CSF secretion prohibits the MDSCs infiltration and blocks tumor development by increasing the number of cytotoxic T cells [61].