PTGS2 and urinary bladder carcinoma: In S. haematobium-associated bladder cancer, S. haematobium eggs are classified as a Group 1 carcinogen [2,17] and are linked to lower expression of tumor suppressor genes p53 [18,19] and p63 [20], of the pro-inflammatory mediator Cyclooxygenase-2 (COX-2) [21,22], and of inducible nitric oxide synthetase [21,23] in humans.