HIF1A and breast cancer: Multiple factors, such as hypoxia inducible factor (HIF)-1α, vascular endothelial (VE)-cadherin, epithelial-mesenchymal transition (EMT), matrix metalloproteinases (MMPs), and several microRNAs (miRs) [2], have been reported to be involved in the formation of VM and regulate the malignant behavior of breast cancer cells [3].