PDCD1 and glioblastoma: A protein-protein interaction (PPI) network based on these markers was constructed (Fig. 4A), and significant differences in the expression of six autophagy-related genes (SQSTM1, LAMP2, CTSB, LAMP1, SERPINA1, RGS19) were identified between the GBM.PD1 and GBM.rec groups.