Data mining revealed that RBL2 is more commonly gaining insertions and deletions in breast cancer than RBL1 and pRb, indicating that 275 out of 997 breast tumours had aberrations in the RBL2 locus whereas the corresponding numbers for RBL1 and pRb were 165 and 249, respectively (Supplementary Fig. 9f ). This evidence concerns the gene RBL1 and breast cancer.