UPK2 and neoplasm: In order to determine whether an S249C mutation in FGFR3 drives tumour pathogenesis in the bladder, we generated a transgenic mouse line that expresses the human FGFR3 IIIb isoform with an S249C mutation under control of the mouse uroplakin II promoter Tg(UroII‐hFGFR3IIIbS249C) (‘FGFR3S249C’).