Increased sensitivity to CDK4/6 inhibitors in breast cancer cell lines with C1orf50 high expression (Fig. 4B, Fig. S4B), and given that patients with high levels of C1orf50 expression have a worse prognosis (Fig. 1D), aggressive administration of CDK4/6 inhibitors may be considered in Luminal breast cancer patients with high C1orf50 expression. Here, CDK4 is linked to breast cancer.