PDCD1 and cancer: Furthermore, SERCA3 expression was closely correlated with MHC, immune activation genes, and immunosuppressive genes such as HLA-DRB1, HLA-E, PDCD1 (PD-1), TGF-B1, CTLA-4, TIGIT, and ICOS in most cancer types (Figures 5(c)–5(e)).