VEGFA and metastatic malignant neoplasm: In addition, the induction of tumour angiogenesis by HIFs through the up-regulated expression of pro-angiogenic factors such as vascular endothelial growth factor (VEGF) in cancer stem/progenitor cells and their differentiated progenies may also promote the tumour growth and formation of invasive and metastatic cancers (Figs 3) [25, 35, 39, 106, 117–119].