Uridine phosphorylase 1 (UPP1) has been reported as an oncogene across a range of malignant tumors, including colorectal cancer (CRC),4 esophageal squamous cell carcinoma (ESCC),5 thyroid carcinoma,6 pancreatic cancer,7 oral squamous cell carcinoma,8 and breast cancer.9 Here, UPP1 is linked to breast cancer.