CD274 and cancer: Recent studies have shown that PKM2 is an important factor in the Warburg effect of cancer cells, immune cells (such as lymphocytes, dendritic cells, macrophages) and immune checkpoints [such as programmed cell death ligand-1 (PD-L1)] in the cancer immune microenvironment, and PKM-2 has different functions in the occurrence, progression and metastasis of cancer 16-18.