RB1 and neoplasm: Schallenberg et al. sought to characterize the heterogeneity of molecular subtypes within MIBC bladder tumors by examining the tumor center and invasive front with IHC markers of molecular subtypes including FGFR3, CCND1, RB1, CDKN2A, KRT5, KRT14, FOXA1, GATA3, TUBB2B, EPCAM, CDH1, and vimentin [38].