Several compounds including betulinic acid, tolfenamic acid and curcumin induce proteasome-dependent degradation of Sp proteins in prostate, pancreatic and bladder cancer cells respectively [22, 23, 38, 39]; however, proteasome inhibitors did not block downregulation of Sp1, Sp3 or Sp4 by sulindac sulfide in SW480 and RKO cells (data not shown). This evidence concerns the gene TFF2 and urinary bladder cancer.