PRF1 and neoplasm: Notably, NK cell-derived extracellular vesicles (NK-EVs) including exosomes typically contain cytotoxic proteins (e.g. perforin, granzyme B, FasL, and TRAIL), originating from NK cells and induce anti-tumor activity against various cancers through the activation of caspase-dependent pathways (Jong et al., 2017; Neviani et al., 2019; Sun et al., 2019; Wu et al., 2019; Zhu et al., 2019).