A number of human cancers, such as lung cancer [4], colon cancer [10], esophageal squamous cell carcinoma [11], gingival squamous cell carcinoma [12], lymphoma [13], renal cell carcinoma [14], neuroblastoma [15], gastric cancer [16], hepatocellular carcinoma [17], cholangiocarcinoma [18], and breast cancer [19], exhibited increased expression of mdig, indicating important role of mdig played in the pathogenesis of human cancers. This evidence concerns the gene RIOX2 and breast cancer.