CAT and bladder transitional cell carcinoma: To verify whether this regulatory mechanism was present in BLCA cells, we transfected empty vector, Parkin, and Parkin loss-of-function mutant (C431S) plasmids into T24, 5637, and UM-UC-3 cells and found that Parkin indeed negatively regulated Catalase (Fig. 4c and Supplementary Fig. 5a).