HIF1A and cancer: It is clear that HIF-1α, the expression of which is induced by hypoxia, further activates the expression of its numerous targets—including matrix metalloproteinases (MMPs), E-cadherin, and transcription factor 3 (TCF3), among others—that enhance cancer metastasis via multiple mechanisms, favoring invasion, extravasation, and metastatic niche formation (63–65).