Mutations in FGFR3 have been associated with less aggressive bladder tumors35 and were localized to BLCA-C5, marked by high expression of COL4A5/COL4A6 and COL10A1, with relatively low expression of fibrillar collagens, and the lowest HR among the 5 BLCA ColClusters (Supplemental Fig. 4). Here, COL4A5 is linked to bladder transitional cell carcinoma.