CD274 and neoplasm: Representatively, tumor cells communicated with programmed cell death 1 (PD-1) to inhibit T-cell proliferation and activation by blocking the Ras-Raf-MEK-ERK and PI3K-Akt signal pathways under the programmed cell death ligand 1 (PD-L1) umbrella, creating an immunosuppressive TME [31, 32].