PRF1 and neoplasm: Murine iNKT cells isolated from liver, thymus, and spleen can kill leukemia, melanoma, lung, breast, and colorectal cancer cells both in vitro and in vivo; they express Fas ligand (FasL), TNF‐related apoptosis‐inducing ligand (TRAIL), granzyme B (GZMB), and perforin (PRF) and can target tumor cells in a CD1d‐dependent or CD1d‐independent manner [29, 33, 35, 36, 37, 38, 39, 40, 41].