AQP2 was E2 dose-dependently increased and expressed in endometrial carcinoma tissues, which was blocked by an estrogen receptor inhibitor, and AQP2 knockdown attenuated E2-enhanced migration, invasion, and adhesion of IK cells.[39] Quantitative RT–PCR revealed that AQP2 was decreased 5.18 times in 127 RCC patients (P < .05), and with the promotion of staging, the expression of AQP2 was reduced gradually (P < .05).[40] The same expression trend was observed in our present study and 13 previous studies. The gene discussed is AQP2; the disease is renal cell carcinoma.