Chung et al. (2017) conducted a study involving 175 immune cells from 11 patients with various BC subtypes, including luminal A, luminal B, HER2, and TNBC. They classified these cells into three categories—T lymphocytes, B lymphocytes, and macrophages—by assessing their gene expression profiles at the single-cell level. Both T lymphocytes and macrophages exhibited features indicative of immunosuppression, with T cells showcasing a regulatory or exhausted phenotype and macrophages presenting an M2 phenotype (Chung et al., 2017). The gene discussed is ERBB2; the disease is breast cancer.