Figure 1: COX-2 immunostaining. (a) A section from a normal urinary bladder mucosa shows low COX-2 immunostaining in the apical portion of umbrella cells (200x). (b) A section from a papillary UCB, (c) a section from an invasive UCB, and (d) a section from high-grade UCB. Cytoplasmic COX-2 immunostaining is higher in invasive and high-grade UCB (100x). Immunohistochemistry was done using an anti-COX-2 antibody, diaminobenzidine as the chromogen, and haematoxylin as a counterstain.