HDAC5 and cancer: However, HDAC5 expression is generally low in both urothelial cancer tissue (according to proteinatlas.org, based on TCGA dataset, HDAC5 transcript levels rank lower, the 14th out of 17 tested cancer types) as well as in urothelial cancer cells (mRNA level 2-fold downregulated as compared to normal uroepithelial cells18) and, most importantly, HDAC5 protein expression is diminished in most urothelial cancer cell lines10.