ABCC4 and neoplasm: The efflux-dominated flow of PGE2 in neoplastic tumors, due to an increased in COX-2 and MRP4 and repressed expression of 15-HPGD and PGT is associated with high levels of PGE2 in the extracellular milieu culminating in the activation of a plethora of pathways that potentiate tumor development [8], [11], [16].