PNPO and glioblastoma: TIMER database mining further found that PNPO expression was significantly associated with the infiltration levels of various immune-associated cells, including B cell, dendritic cells, CD8+T cells, CD4+T cells, neutrophils, and macrophages in BRCA, GBM, KICH, LIHC, SARC, STAD, THCA, and THYM.