VSIR and cancer: (2) VISTA expression levels correlated positively with the relative abundance of almost all critical immunomodulators regardless of their function as immunoinhibitors, immunostimulators, or major histocompatibility complexes (MHCs) across 30 types of cancers, including but not limited to, the critical immune checkpoints such as PD-1, PD-L1, CD80, and CD86 (Fig. 4b–d).