*4.13. Mutation Analysis*

To explore potential *MAP1B* mutation in UC, we randomly selected 15 UTUC and 15 UBUC cases (Table S1) with high protein expressions of *MAP1B* for mutation analysis. Mutation analyses were performed by using an ABI3100 sequencer targeting eight pathogenic point mutations occurring in other cancer types according to the database of COSMIC repository (https://cancer.sanger.ac.uk/ cosmic/gene/analysis?ln=HSD11B1#variants). Validated *MAP1B* mutations and primers sets are shown in Table S2. The PCR amplification started with an initial denaturation step at 95 ◦C for 15 min, followed by 35 cycles of 95 ◦C for 30 s, 58 ◦C for 30 s, and 72 ◦C for 30 s, and a final extension step at 72 ◦C for 10 min. Then, these amplicons generated in individual PCR reactions were analyzed by direct sequencing.
