BACKGROUND:Ten-eleven translocation (TET) family proteins are recently discovered DNA dioxygenases that convert methylcytosine to hydroxymethyl cytosine, which is essential for regulating cel proliferation and differentiation, but the expression pattern of TET family proteins in human dental pulp cel s is stil unclear. OBJECTIVE:To investigate the expression pattern of TET family proteins during the differentiation of human dental pulp cel s. METHODS:Cel ular distribution and expression of TET family proteins were determined by immunofluorescence in human dental pulp cel s that were cultured and isolated using digestion method. The protein levels of TETs during cel passage (P1-P7) were detected with western blot assay, and their potential changes during odontogenic induction (7 and 14 days) were confirmed using real-time quantitative PCR and western blot analyses at mRNA and protein levels, respectively. RESULTS AND CONCLUSION:Al TETs were expressed in the nucleus and the cytoplasm of human dental pulp cel s During serial cel passage, TET1 protein expression was increased until the 6th passage, TET2 significantly increased at the 2nd and 3rd passages and then decreased (P<0.05), and TET3 showed no statistical y significant change (P>0.05). Both mRNA and protein expression levels of al TETs were elevated during odontogenic induction (P<0.05). These results indicated that TETs may contribute to cel differentiation of human dental pulp cel s.