A number of human cancers, including lung cancer [2], colon cancer [5], esophageal squamous cell carcinoma [6], gingival squamous cell carcinoma [7], lymphoma [8], neuroblastoma [9], gastric cancer [10], hepatocellular carcinoma [11], cholangiocarcinoma [12] and breast cancer [13], exhibited increased expression of the mdig mRNA or protein. Here, RIOX2 is linked to breast cancer.