IL13RA1 and urinary bladder neoplasm: To determine whether human IL-4R expression is maintained in xenografts, we examined mRNA expression by real-time RT-PCR for IL-4Rα, IL-13Rα1, and IL-2RγC. These bladder tumor specimens showed three to six times higher expression of IL-4Rα mRNA compared to adjacent tissue specimens in all 12 samples (P ≤ 0.001).