HIF1A and neoplasm: Hypoxic tumor microenvironment triggers AMPK activation in cancer cells, which stabilizes HIF-1α and subsequently induces the transcriptional upregulation of key metabolic regulators including glucose transporters (GLUT1, GLUT3 and GLUT4), glycolytic enzymes (HK2 and PFKFB2), and serine biosynthesis pathway (SSP) enzymes.