MRC1 and urinary bladder cancer: A detailed analysis of mutations in the 10 ultra-mutated cases of bladder cancers with TMB above 30 mutations/MB discloses that, besides the above-mentioned sample with the likely oncogenic POLE P286R mutation, which also possesses a MSH2 likely oncogenic mutation, no other cases contain likely pathogenic mutations in MMR related genes or the proofreading polymerases (Table 4).