Specifically, transfection of each miR-29 member into A549 lung cancer cells led to a reduction in DNMT3A and DNMT3B mRNA levels, which correlated with decreased global DNA methylation and the re-expression, in both A549 and H1299 lung cancer cells, of tumor suppressor genes such as FHIT and WWOX, normally silenced through promoter methylation in lung cancer. Here, DNMT3A is linked to lung cancer.