It has been shown that NPM overexpression was present in several human solid tumours, including gastric cancer (Tanaka et al, 1992), colon cancer (Nozawa et al, 1996), bladder cancer (Tsui et al, 2004), prostate cancer (Subong et al, 1999), thyroid cancer (Onda et al, 2004), and ovary cancer (Zhang, 2004). This evidence concerns the gene NPM1 and urinary bladder cancer.