FGFR3 and in situ carcinoma: In addition, BC usually shows affectation of the FGFR3/RAS or the TP53/RB1 signaling pathways, with mutations in FGFR3 frequently occurring during the hyperplasia of the urothelium, and mutations in TP53 facilitating the transition from dysplasia to invasion via the CIS pathway [30].