Large research consortia such as the Molecular Taxonomy of Breast Cancer 
International Consortium (METABRIC), The Cancer Genome Atlas and International 
Cancer Genomics Consortium are systematically interrogating large sets of tumor 
samples through integrated analysis of genome-wide DNA copy number and promoter 
methylation, transcriptome-wide RNA expression, protein expression and 
exome-wide sequencing. A recent METABRIC study explored the effects of 
cis-acting and trans-acting factors of gene expression regulation in breast 
cancer. By making their data sets publicly available, these large consortia are 
inviting new types of analysis that have the potential to drive breast cancer 
research into previously unexplored avenues.