CD8A and breast cancer: ALDH1A1 is an enzyme that plays a crucial role in various cancers, particularly in breast cancer, where it activates the TAK1-NFkB signaling pathway by reducing the intracellular pH of tumor cells, increases the secretion of GM-CSF, promotes the proliferation of myeloid-derived suppressor cells (MDSCs), inhibits the activity of CD8+ T cells, and thus promotes tumor growth (Liu et al., 2021).