PDCD1 and gastric cancer: Secondly, we unveil a novel mechanism of immune evasion of GC cells: HSPA4 overexpression in GC cells decreases CD58 via ALKBH5/CD58 pathway, activates PD1/PDL1 axis, decreases cytotoxicity and infiltration of CD8+ T cells and induces tumor immunosuppressive microenvironment.