Our findings establish NIK as a pivotal regulator of T cell metabolism in anti-tumor immunity and highlight a posttranslational mechanism of metabolic regulation involving the G6PD-NADPH redox system. CoIP assays revealed a strong physical interaction between NIK and G6PD in both T cells and transiently transfected 293 cells, suggesting G6PD to be a direct target of NIK. Using a phosphoprotein gel analysis approach, we demonstrated that NIK expression stimulated G6PD phosphorylation. To further study the mechanism, we performed mass spectrometry identify phosphorylation sites of G6PD stimulated by NIK