PTGER4 and ovarian cancer: Reader et al. [196] showed that inhibition of EP4 receptors for the downstream product of COX enzymes, PGE2, can sensitize chemotherapy-resistant cancer cells that over-express class III β-tubulin to taxanes. EP4 is overexpressed in a variety of epithelial ovarian histologies [171] and upregulation of class III β-tubulin can be provoked by inflammatory stimuli [197] and is associated with aggressive biologic behavior in ovarian cancer [198,199].