Altogether, these results imply that breast cancers, particularly the aggressive breast cancer subgroup, display frequent disruption in the RBL2-tumour suppressor pathway (Cyclin D, CDK4/6, E2F, pRb, and RBL2), which regulates G1/S phase transition but also exhibit an increase in WNT signalling components. The gene discussed is CDK4; the disease is breast carcinoma.