Although BCa has one of the highest proportions of APOBEC-induced mutations, and APOBEC3A and APOBEC3B gene expression are significantly upregulated in tumor tissue relative to normal urothelium12 the roles of APOBEC3A and APOBEC3B have not been systematically explored in bladder cancer. This evidence concerns the gene APOBEC3B and urinary bladder carcinoma.