CD8A and breast cancer: To this end, we FACS‐analysed lymphocytes from human breast cancer patients (Figure 6A) and assessed the CD8 expression on tumour‐infiltrating cytotoxic T lymphocytes (Figure 6B) in connection to clinical parameters such as Ki67 expression in cancer cells, or the number of affected lymph nodes and distant metastasis as indicators for cancer progression (Figure 6C).