To study whether a DA1 receptor antagonist can prevent renal cyst formation, the DA1 antagonist SCH23390 was administered in 8-week-old mice through the drinking water (0.1 mg/kgBW/day) for 6 weeks in control (Pkd2fl/fl) and Pkd2–/– (Pkd2fl/fl;Pax8-rtTA;Tet-O-Cre)mice 2 weeks after induction, with doxycycline from p28 to p42. This evidence concerns the gene PKD2 and cystic kidney disease.