HIF1A and breast cancer: declared that invasive BC cells under hypoxic conditions released small EVs containing hypoxia-inducible factor-1α (HIF-1α), thus then altered normal mammary epithelial differentiation, expanded progenitor cell populations, and induced systemic immunosuppression by increasing S100A9 release from myeloid cells, promoting epithelial-mesenchymal transition (EMT) and luminal cell invasion (29).