Alterations in gene expression are central to the malignant phenotype. In this issue, Al-Ahmadi et al elegantly demonstrate that one key mechanism that determines invasiness in breast cancer is likely to be dysregulation of mRNA stability. This is achieved by altered expression of the proteins TTP and HuR, which bind 3′ untranslated region (UTR) elements in cancer-related genes. The authors link this to the expression of a miRNA, miR-29a, and show that anti-miR-29a treatment can reverse the invasive phenotype in vitro. This further highlights the important roles of mRNA UTRs in malignant transformation, and the importance of investigating post-transcriptional disease mechanisms. Such mechanisms have the potential to provide novel therapeutic targets, as well as being vital to further our understanding of cancer biology. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.