We utilized, as our starting materials, (i) normal urothelia (NU) from wild-type mice, (ii) simple urothelial hyperplasia (SUH) from heterozygous Upk2-HRAS*/WT transgenic mice (2-3 months old; [9]), (iii) nodular urothelial hyperplasia (NUH) from young homozygous Upk2-HRAS*/* transgenic mice (1-month old; [10]), and (iv) low-grade, papillary urothelial carcinoma (UC) from older homozygous Upk2-HRAS*/* transgenic mice (5-months old; [10]) (Figure 1A). Here, UPK2 is linked to urothelial hyperplasia.