Activation of TET1 by hypoxia/HIF-2α and knockdown of TET1 mitigated hypoxia-induced epithelial-mesenchymal transition. (a) Western blot analysis showed the activation of TET1 by hypoxia. N: normoxia; H: hypoxia. (b) Overexpression of HIF-2α activated TET1 expression using western blot analysis. (c) Knockdown of HIF-2α abolished the activation of TET1 by hypoxia. (d) Reporter gene assays showed the activation of TET1 proximal promoter by HIF-2α. The asterisk (*) indicates statistical significance (P <0.05) between experimental and control transfections. pXP2-Tet1-381 or pXP2-Tet1-158 vector alone was used as the control transfection. Error bars indicate standard deviations (s.d.) of triplicate luciferase activity. (e) Knockdown of TET1 mitigated the process of hypoxia-induced EMT.