Mutations in the Tumor Protein 53 (TP53) gene are observed in about 37% of patients [4], and while mutations in the retinoblastoma (RB1) gene occur in only 2.5% of invasive BC patients (Fig. 1A), the dysregulation of RB1 and genes in the RB1 pathway, including Cyclin D1, p16Ink4a, CDK4, and Cyclin E, is observed in approximately 27% of patients (Fig. 1A). Here, CDK4 is linked to breast cancer.