CD8A and breast cancer: Our group previously reported that high expression of Polo-like kinase 1 (PLK1), which plays a pivotal role both in the p53-mediated regulation of DNA damage repair and in mitosis, was associated with homologous recombination deficiency as well as high levels of CD8+ T cells, M0 and M1 macrophages, low levels of M2 macrophages, and high immune cytolytic activity in breast cancer [32,33].