CD274 and neoplasm: Recent studies have discovered that beyond upregulating the expression of programmed death-ligand 1 (PD-L1) on cellular surface1,2, tumor cells (e.g., melanoma) secrete a high level of PD-L1 on exosome, a particular form of extracellular vesicle derived from the cellular endocytic pathway3, to interfere in systemic immune state.