KRAS and neoplasm: KRAS-induced secretion of granulocyte-macrophage colony-stimulating factor (GMCSF) results in an influx of CD11b + Gr1+ immunosuppressive cells in PDAC, and ablation of this cytokine impairs immunosuppressive cell accumulation in PDAC tumor tissue, consequently resulting in an increase in the CD8+ T cell frequency [70].