PRF1 and neoplasm: The primed CD8+ T-cell is now able to recognize the TA-MHC I complex on the surface of other tumor cells and, once bound to other tumor cells, can induce apoptosis through either death receptor signaling, which involves binding of the CD8+ T-cell Fas ligand (FasL) with the tumor cell FAS receptor (FasR), or through the release of the granzyme B and perforin.