The EdU assay (Figures 4A, B) and MTT assay (Figure 4C) were performed, and the results showed that PR-BC-exo with gp96 expression significantly suppressed cell viability and proliferation in the CD8+ T cells, while PR-BC-exo with gp96 deficiency had little effects on the above cellular functions (Figures 4A–C). This evidence concerns the gene CD8A and breast cancer.