POU5F1 and urinary bladder cancer: Consistent with downregulation of the levels of COX2 and PGE2 as well as inhibition of STAT3 phosphorylation/activation, the levels of both CK14 and OCT3/4 were repressed by metformin in a dose-dependent manner (Figure 6A); suggesting metformin may repress bladder cancer development through the COX2/STAT3 pathway.