CD8A and neoplasm: Sustained NRF2 activation induced by loss of Pten and Keap1 leads to reprogrammed cellular pentose phosphate pathway (PPP) and an immunosuppressive microenvironment, characterized by specific upregulation of programmed death ligand-1 (PD-L1) on tumor cells and an enhanced expression of PD-1 on CD8 T cells (50).