CDKN1A and breast cancer: The accumulation of evidence has demonstrated that CDC20 is dramatically elevated in human malignancies (including pancreatic cancer, breast cancer, and lung cancer), and CDC20 contributes to the malignant progression of cancer by degradation of its downstream target genes (such as CDKN1A (P21), Cyclin B1, and Bim) through ubiquitination, making it a promising target for cancer treatment [24].