IHC staining revealed that in 4T1M3OVA tumors, the levels of bisecting GlcNAc and pro-apoptotic protein Bax were increased, and the levels of PD-L1, cell proliferation index Ki67 and anti-apoptotic protein Bcl-2 were decreased, indicating that CD8+ TOT−1 cells promoted the apoptosis of BC cells with high bisecting GlcNAc levels (Fig. 5I&J). Here, CD8A is linked to breast cancer.