PRF1 and cancer: Away from the TME, NK cells cultured in hypoxia for 48 hours produce larger yields of NKEVs with increased total protein, FasL, perforin, and granzyme B concentrations, increased cytotoxicity against breast (MCF-7) and ovarian (A2780) cancer cells in vitro, and increased inhibition of the migration and proliferation of these cancer cells (93).