APOBEC3B and urinary bladder cancer: As we found A3B1 the primary mutagenic APOBEC enzyme in bladder tumors, enhancing A3B exon 5 skipping might help to restrict APOBEC-mediated mutagenesis, including FGFR3-S249C mutation in bladder cancer, as well as prevent tumor progression and recurrence, clonal evolution, and resistance to chemotherapy (Fig. 8).