DNMT3B and acute myeloid leukemia: As an example, miR-29b expression in acute myeloid leukemia cells reduced the expression, at both RNA and protein levels, of DNA methyltransferases DNMT1, DNMT3A, and DNMT3B. The downregulation of DNMT3A and DNMT3B is the result of a direct interaction between miR-29b and the 3’ untranslated regions of these genes, while the decrease of DNMT1 expression was reached indirectly via downregulation of Sp1, a known transactivating factor of the DNMT1 gene.