PVR and cancer: The HCC827, MG-63, and NCI-H1650 cell lines—each with high natural expression of immune checkpoint proteins PD-L1, CD155, and B7-H3, respectively—were developed into an IFNγ-IFNγR JAK-STAT GAS-Luc2 reporter systems that are capable of reliably reporting the activity of IFNγ from activated primary human immune cells that mimic the in vivo cancer cell killing events.