HIF1A and cancer: Previous studies have demonstrated that multiple signaling pathways including phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MAPK) signaling pathways mediate HIF-1α and VEGF expression induced by hypoxia or insulin-like growth factor-1 (IGF-1) in various cancer cells [27]–[30].