In ARPKD and ADPKD model mice, the protein expression level of the P2X7 receptor was significantly elevated in cystic epithelial cells.[46,47] Pannexin-1 (PANX-1), an ion channel capable of releasing ATP, is also significantly more expressed in cystic epithelial cells than in normal tubular epithelial cells. The gene discussed is PANX1; the disease is autosomal dominant polycystic kidney disease.