IFNB1 and cancer: Amino acid substitutions in the PIV5 shared P/V region resulted in a mutant (P/V-CPI-) which overexpresses viral RNA and protein, is a potent inducer of IFN-β and proinflammatory cytokines, is defective in blocking IFN signaling, and induces cell death in cancer cells [14,15,16,21,22,23].