In recent investigations, we found that the mechanism accounting for overexpression of DNMT3b among breast cancer cell lines that express aberrant DNA hypermethylation is related to concurrent loss of microRNAs (miRs) that post-transcriptionally regulate DNMT3b mRNA, including miR-29c, miR-148a, miR-148b, miR-26a, miR-26b and miR-203 (38). This evidence concerns the gene DNMT3B and breast cancer.