While increased activity of Na+/K+-ATPase promotes cancer development, its reduced expression and activity have also been detected in certain human tumors, including renal cell carcinoma, urothelial cancer and different types of cancer cell lines [21], which is in concordance with the biphasic function of NKAIN2 as either TSG or oncogene in different cell types. This evidence concerns the gene NKAIN2 and cancer.