TET1 and neoplasm: In the present study, we measured TET1/2/3 mRNA expression levels in 50 matched ESCC samples, compared with the corresponding non-tumor tissues, TET2 and TET3 gene expression was significantly reduced in tumor tissues, but downregulation of only TET2 was significant associated with decreased 5-hmC, suggesting that decreased 5-hmC expression primarily reflects decreased TET2 expression in ESCC.