The most prominent driver events identified (or confirmed) by these studies include amplification of oncogenes like ERBB2, CCND1, ZNF218 or EMSY, as well as deletion of tumour suppressors like TP53 and PTEN. The largest study to date, performed by the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), suggests that many more putative driver events exist, with many of these being specific to certain breast cancer subtypes [4]. This evidence concerns the gene PTEN and breast cancer.