In human hepatocellular carcinoma, B7S1 expression is reportedly upregulated on APCs, and its putative receptor is co-expressed with PD-1 on activated early CD8+ TILs, to promote T cell exhaustion and depress anti-tumor immune response via upregulating Eomes (Li et al., 2018). The gene discussed is VTCN1; the disease is hepatocellular carcinoma.