Re-analysis of publicly available data revealed that CDK12 may constitute a tumour suppresser gene as it is recurrently targeted not only by DNA rearrangements in breast (2.6% of unselected breast cancers; 13% of HER2-amplified breast cancers) and 1/17 (5%) HER2-amplified gastric cancers 51, but also by nonsense mutations in 1.5% of triple-negative breast cancers 43. This evidence concerns the gene CDK12 and breast cancer.