In vitro, the RT112 bladder cancer cell line was derived from a human bladder tumor and expresses the FGFR3‐TACC3 fusion protein, while the UMUC‐14 cell line expresses an endogenous activated mutant form of FGFR3 (FGFR3‐S249C).33, 44. Here, FGFR3 is linked to urinary bladder cancer.