PRF1 and neoplasm: In tumor immune surveillance, the major cytotoxic lymphocytes, CD8+ T cells and natural killer (NK) cells, can direct perforin-dependent tumor cell killing and release several inflammatory cytokines, such as IFN-γ and TNF, to promote antitumor immunity through antigen presentation (Voskoboinik et al., 2015; Kearney et al., 2017).