TET1 and B-cell chronic lymphocytic leukemia: We show that treatment of CLL cell lines with 5-aza 2 ́-deoxycytidine (DAC) results in the activation of miR26A1, which causes decrease in both mRNA and protein levels of EZH2, which in turn results in the decreased occupancy of EZH2 over the TET1 promoter and consequently the loss of TET1 expression.