Histological analysis confirmed that the generated tumors were in most cases urothelial cell carcinomas, ranging from 40% (p53 + Cmyc) up to 100% of experimental animals (p53 + Kras + Cmyc) and of those tumors shown to be urothelial cell carcinomas, we detected the primary tumor in the bladder in almost all cases (Supp. Here, KRAS is linked to transitional cell carcinoma.