HIF1A and breast cancer: In response to reduced O2 availability, hypoxia-inducible factor 1 (HIF-1) mediates the transcriptional activation of genes encoding proteins that are required for many important steps in breast cancer progression, such as angiogenesis, cancer stem cell maintenance, cell motility, epithelial-mesenchymal transition, extracellular matrix remodeling, metabolic reprogramming, metastasis, and resistance to therapy [3-6].