Hu et al. (2018) reported microRNA-210 was involved in the regulation of TET1 under hypoxia status. Lin et al. (2017) showed HIF-1a could regulate the hypoxia-induced expression of TET in hepatoblastoma HepG2 cells, whereas Tsai et al. (2014) showed the HIF-1a knockdown had no effect on the TET1 expression in cancer cell lines. It will be explored in future studies. Combined with the reporter gene assay of HIF-2α and TET1 (Tsai et al., 2014), we speculate that the hypoxia microenvironment may induce the EMT of endometrial epithelial cells via the activation of TET1 partly regulated by HIF-2α. The gene discussed is EPAS1; the disease is cancer.