CSF2 and gastric cancer: In GC, the expression of PD-L1 of neutrophils can be induced by tumor derived granulocyte-macrophage colony-stimulating factor (GM-CSF), which can be activated through Janus kinase (JAK) - signal transducer and activator of transcription 3 (STAT3) pathway, to a large extent, inhibiting tumor immunity and promote progression of GC (35).