EPAS1 and cancer: Cancer cells in solid tumors often suffer from hypoxic stress and adapt to this micro-environment via the activation of Hypoxia inducible factor (HIF), a heterodimeric transcription factor composed of either HIF-1α or HIF-2α (initially identified as endothelial PAS domain protein (EPAS1)) and HIF-1β/ARNT subunits Semenza (2012); Rankin et al. (2016); Rankin and Giaccia (2016).