It has most widely been described in the regulation of epithelial cell proliferation within several different cancer models including prostate, lung, ovarian, and renal cell carcinoma.59 SPOP is downregulated in colorectal cancers, and inactivation promotes metastasis, suggesting a role as a tumor suppressor.60 The exact physiological function of TPMT has yet to be elucidated; however, it is a key enzyme in the metabolism of immunosuppressive thiopurine analogues commonly used in the treatment of UC. Here, SPOP is linked to renal cell carcinoma.