For example, in the case of transitional cell carcinoma (TCC) that represents superficial bladder tumors and invasive bladder cancers, the superficial bladder tumor cells expressed p16 after limited in vitro passage and senesced as did the normal human uroepithelial cells, while all the muscle invasive TCCs contained altered p16 or pRB and bypassed senescence [215]. The gene discussed is CDKN2A; the disease is transitional cell carcinoma.