PRF1 and neoplasm: Upon activation by α-galactosylceramide (α-GalCer), a synthetic glycolipid antigen loaded onto CD1d, iNKT cells exhibit dual effector functions: 1) rapid secretion of both Th1-type (e.g., IFN-γ, TNF-α) and Th2-type (e.g., IL-4, IL-13) cytokines (138); 2) direct cytotoxic activity against tumor cells via perforin/granzyme pathways (139).