HIF1A and esophageal squamous cell carcinoma: Our findings demonstrated that the residues located between 446 and 578 within the C-terminal region of Pol ι are essential for the deubiquitination, stabilization, and functional activity of HIF-1α and blocking the specific binding of Pol ι and USP7 inhibits HIF-1α induced EMT in ESCC cells (Fig. 7).