FGFR3 and urinary bladder carcinoma: Mutations in PIK3CA, FGFR3, and ERBB2 highlight the relevance of the receptor tyrosine kinase (RTK)–RAS–PI3K signaling cascade in urothelial cancer pathogenesis, in line with previous studies documenting PI3K pathway alterations in 20–30% of bladder cancers [25].