PVR and neoplasm: It has been reported that chemotherapeutic agents induce the expression of various NK cell-activating ligands on tumor cells; these ligands include NKG2D ligands, Fas (apoptosis-stimulating Fragment), poliovirus receptor (CD155), Nectin-2 (CD112), B7-H6 (B7 family member), and TRAIL (tumor necrosis factor-α-related apoptosis-inducing ligand)-R1/R2.