In addition, upregulation of p16 (CDKN2A) at the protein level [24] and an increase in the expression of E2F targets and other cell-cycle-related pathways, including Myc regulation [19], has been reported in patients with resistant BC, highlighting the critical role of these genes in the clinical efficacy of CDK4/6 [19,20]. The gene discussed is CDK4; the disease is breast cancer.